File Explorer normally displays miniature previews of pictures, videos, PDFs and certain other supported files. It can also display the contents of a selected file in the Preview Pane without requiring you to open the file.

When these features stop working, you may notice problems such as:

• JPG, PNG and other pictures display generic icons instead of images.
• Videos show only the media player's icon.
• PDF files do not display thumbnails.
• The Preview Pane is completely blank.
• File Explorer reports "No preview available."
• A particular file type cannot be previewed.
• Thumbnails work in some folders but not others.
• Preview Pane works for images but not PDFs or Office documents.
• Previously working previews suddenly disappear.

Although thumbnails and the Preview Pane appear similar, Windows handles them differently. Therefore, it is possible for thumbnails to work while the Preview Pane fails, or vice versa.

This guide covers the most common causes and solutions for Windows 10 and Windows 11.

Part 1 – Understand Thumbnails vs Preview Pane

What Is a Thumbnail?

A thumbnail is a small visual representation of a file displayed directly inside File Explorer.

For example, instead of:

photo.jpg → generic JPG icon

Windows may display a miniature version of the actual photograph.

Thumbnails are commonly generated for:

• JPG/JPEG
• PNG
• BMP
• GIF
• WebP
• Videos
• PDFs when a compatible thumbnail handler is installed
• Some Office documents
• Certain design and media formats

Windows stores generated thumbnails in a cache to improve File Explorer performance.

What Is the Preview Pane?

The Preview Pane is a separate section of File Explorer that attempts to display the selected file's contents.

Depending on the installed software and preview handlers, Windows may preview:

• Images
• Text files
• PDFs
• Microsoft Word documents
• Excel workbooks
• PowerPoint presentations
• Some videos
• Other supported document formats

A thumbnail problem therefore does not necessarily mean that the Preview Pane is also defective.

Part 2 – Basic Checks

Before performing advanced troubleshooting, restart the computer.

A temporary File Explorer, thumbnail-cache or preview-handler problem may disappear after Windows restarts.

If the problem remains, continue with the following methods.

Solution 1 – Make Sure Thumbnail Display Is Enabled

One of the most common causes is the File Explorer option:

Always show icons, never thumbnails

When enabled, Windows deliberately disables thumbnail previews.

Steps

1. Open File Explorer.
2. Open Folder Options / File Explorer Options.

In Windows 11:

File Explorer → three-dot menu → Options

Depending on the current Windows version, the interface may differ slightly.

3. Select the View tab.
4. Locate:

Always show icons, never thumbnails

5. Make sure this option is unchecked.
6. Click Apply.
7. Click OK.

Close and reopen File Explorer.

Check whether image and video thumbnails now appear.

Solution 2 – Enable Thumbnail Display in Windows Performance Settings

Windows has another setting that controls whether thumbnails are displayed.

Press:

Windows + R

Enter:

sysdm.cpl

Press Enter.

Open:

Advanced → Performance → Settings

Under Visual Effects, make sure the following option is enabled:

Show thumbnails instead of icons

Click:

Apply → OK

Restart File Explorer or restart Windows.

Solution 3 – Change the Folder View

Thumbnails are difficult or impossible to notice when File Explorer is configured to display very small icons or certain list-style views.

Open the affected folder and change the view to:

• Medium icons
• Large icons
• Extra large icons

If thumbnails suddenly appear, Windows itself may be functioning correctly and the previous folder view simply was not suitable for displaying them.

Solution 4 – Clear and Rebuild the Windows Thumbnail Cache

Windows stores generated thumbnails in cache databases. If these files become corrupted, File Explorer may display generic icons even when thumbnail settings are correct.

Rebuilding the cache is one of the most effective solutions.

Method A – Using Windows Storage Settings

Open:

Settings → System → Storage → Temporary files

Look for Thumbnails if it is available.

Select it and remove the cached thumbnail data.

Windows automatically creates new thumbnails when you browse your folders again.

The first opening of a large image or video folder may therefore be slower than normal.

Solution 5 – Delete Thumbnail Cache Manually

If the normal cleanup method does not resolve the problem, the thumbnail database can be rebuilt manually.

Close unnecessary applications first.

Open Command Prompt as Administrator.

Run:

taskkill /f /im explorer.exe

Then:

del /f /s /q /a "%LocalAppData%\Microsoft\Windows\Explorer\thumbcache_*"

Finally restart Explorer:

start explorer.exe

Windows will recreate the thumbnail cache.

Important

Your original photos, videos and documents are not deleted by this procedure.

Only Windows-generated thumbnail cache files are removed.

Solution 6 – Restart Windows Explorer

File Explorer itself may occasionally stop generating previews correctly.

Press:

Ctrl + Shift + Esc

to open Task Manager.

Locate:

Windows Explorer

Right-click it and select:

Restart

The desktop and taskbar may briefly disappear and reload.

Check File Explorer again.

Part 3 – Fix Preview Pane Not Working

Solution 7 – Make Sure Preview Pane Is Enabled

The Preview Pane may simply have been disabled.

In File Explorer, enable:

View → Show → Preview pane

On many Windows systems you can also use:

Alt + P

Select a supported file and check the right-hand Preview Pane.

Solution 8 – Enable Preview Handlers

Windows uses special components called preview handlers to display many file types inside the Preview Pane.

Open:

File Explorer → Options → View

Make sure:

Show preview handlers in preview pane

is enabled.

Click:

Apply → OK

Restart File Explorer.

Solution 9 – Test Different File Types

This is an important diagnostic step.

Try previewing:

1. JPG image
2. PNG image
3. TXT file
4. PDF document
5. Word document

The results can identify where the problem exists.

For example:

Images and TXT preview correctly, but PDF does not

This usually indicates a PDF preview-handler problem rather than a general File Explorer problem.

Nothing previews

This suggests a Windows/File Explorer configuration or system-level problem.

Only Office documents fail

The issue may be related to Microsoft Office preview handlers, Office installation or file security.

Solution 10 – Check Whether the File Is Blocked

Files downloaded from the Internet, received through email or copied from another computer may contain Windows security metadata indicating that they originated from another source.

For a trusted file:

1. Right-click the file.
2. Select Properties.
3. Look near the bottom of the General tab.
4. If an Unblock option appears, select it.
5. Click Apply.
6. Click OK.

Re-select the file in File Explorer and test the Preview Pane.

Only unblock a file when you trust its source.

Solution 11 – PDF Thumbnails or PDF Preview Not Working

PDF preview capability may depend on the installed PDF application and its Windows shell integration.

If PDF files are the only affected type:

• Update your PDF reader.
• Repair the PDF application.
• Check its preferences for Windows Explorer thumbnail/preview integration.
• Restart Windows after changing PDF integration settings.
• Verify the PDF file itself opens normally.

If using Adobe Acrobat or Acrobat Reader, check the application's current preferences for options related to PDF thumbnail previews in Windows Explorer.

The exact wording and availability can vary by Acrobat version.

Solution 12 – Word, Excel or PowerPoint Preview Not Working

If the Preview Pane works for images and text files but fails for Microsoft Office documents, repair the Office installation.

Open:

Settings → Apps → Installed apps

Find your Microsoft 365 or Microsoft Office installation.

Choose its modification/repair option.

Start with Quick Repair if available.

If that does not solve the problem, Online Repair may provide a more complete repair, but it can take longer and may require an Internet connection.

Restart Windows afterward.

Solution 13 – Reset File Explorer Folder Options

Incorrect folder configuration can sometimes cause unusual thumbnail behavior.

Open:

File Explorer Options

Select the View tab.

Choose:

Restore Defaults

Then click:

Apply → OK

Test the affected folder again.

Note that this resets certain File Explorer view preferences.

Solution 14 – Check Default Applications and File Associations

Thumbnail and preview generation can sometimes depend on the application associated with a file type.

For example, if PDF preview stopped working after uninstalling or changing a PDF application, the registered PDF preview component may no longer be available.

Open:

Settings → Apps → Default apps

Check the affected extension, such as:

• .jpg
• .png
• .pdf
• .mp4

Assign a suitable application.

Restart File Explorer afterward.

Solution 15 – OneDrive Files Not Showing Thumbnails

Cloud files can behave differently from locally stored files.

If the affected files are stored in OneDrive, first determine whether the files are fully available locally.

Right-click the required OneDrive file or folder and, where appropriate, choose:

Always keep on this device

Allow synchronization/download to finish and test again.

If local files display thumbnails correctly but online-only files do not, the problem may be related to cloud availability or synchronization rather than the Windows thumbnail system itself.

Solution 16 – Network Drive Thumbnails or Preview Not Working

If thumbnails work on the local C: drive but not on:

• NAS storage
• File server
• Shared folder
• Mapped network drive

test by copying one affected file temporarily to a local folder.

For example:

C:\Temp

If the thumbnail or Preview Pane works locally, investigate:

• Network performance
• File permissions
• Server/share configuration
• File availability
• Security restrictions
• Application preview-handler behavior over network paths

This test helps separate a Windows Explorer problem from a network-specific problem.

Solution 17 – Check Free Disk Space

Windows requires working storage space for caches and temporary files.

Open:

Settings → System → Storage

Check the free space on the Windows system drive.

If the C: drive is almost completely full, remove unnecessary temporary files and unused data.

Avoid manually deleting unknown files from Windows system folders.

Solution 18 – Repair Windows System Files with SFC

Corrupted Windows components may affect File Explorer and related shell functions.

Open Command Prompt or Windows Terminal as Administrator.

Run:

sfc /scannow

Wait until the scan reaches 100%.

Possible results include:

• Windows did not find any integrity violations.
• Windows found corrupt files and successfully repaired them.
• Windows found corrupt files but was unable to fix some of them.

Restart the computer after repairs.

Solution 19 – Repair the Windows Component Store with DISM

If SFC does not solve the problem, use DISM.

Open Command Prompt or Terminal as Administrator and run:

DISM /Online /Cleanup-Image /RestoreHealth

Allow the operation to complete.

Then run SFC again:

sfc /scannow

Restart Windows.

DISM can require Internet access or an appropriate repair source in some environments.

Solution 20 – Test a New Windows User Account

If thumbnails and previews remain broken, determine whether the problem affects Windows globally or only the current user profile.

Create a temporary local Windows account and sign in.

Test File Explorer.

If thumbnails and Preview Pane work normally in the new account, the original Windows profile may contain damaged Explorer settings, caches or per-user shell configuration.

This is a valuable diagnostic step before considering major Windows repairs.

Solution 21 – Investigate Third-Party Shell Extensions

Applications can install extensions into File Explorer.

Examples include:

• PDF software
• Compression utilities
• Cloud storage clients
• Media software
• Version-control software
• Antivirus/security applications
• Image-management applications

A defective shell extension or preview handler can make File Explorer unstable or interfere with previews.

A useful clue is that the problem started immediately after installing or updating an application.

Try updating, repairing or temporarily uninstalling the suspected application.

Avoid deleting random shell-extension registry entries without identifying their purpose.

Solution 22 – Video Thumbnails Not Showing

If pictures display thumbnails but videos do not, the problem may be related to:

• Video format
• Codec support
• Damaged media file
• Thumbnail handler
• Media application
• Unsupported encoding

Test several known-good MP4 files.

If MP4 thumbnails work but another format does not, Windows may lack support for the codec used by that particular media format.

Do not install codec packs from unknown websites. Poor-quality codec packages can create additional File Explorer and security problems.

Solution 23 – Check Whether the Original File Is Damaged

Windows cannot reliably create a thumbnail or preview for a corrupted file.

Try opening the file normally.

If the associated application also cannot open it, the problem may be with the file rather than File Explorer.

Test several files of the same type before changing Windows configuration.

Recommended Troubleshooting Sequence

For most computers, use this order:

Step 1: Restart Windows Explorer.

Step 2: Disable Always show icons, never thumbnails.

Step 3: Enable Show thumbnails instead of icons.

Step 4: Enable the Preview Pane with Alt + P.

Step 5: Enable Show preview handlers in preview pane.

Step 6: Clear the thumbnail cache.

Step 7: Test JPG, TXT, PDF and Office files separately.

Step 8: Check whether downloaded files are blocked.

Step 9: Repair the application responsible for the affected file type.

Step 10: Run SFC and DISM.

Step 11: Test with another Windows user account.

This approach avoids unnecessary system changes and helps identify whether the issue is caused by Windows itself or by a specific application/file type.

Quick Diagnostic Table

Problem	Most Likely Area to Check
All files show icons instead of thumbnails	File Explorer thumbnail setting
Pictures have no thumbnails	Thumbnail cache or Explorer settings
Videos only have no thumbnails	Codec/format/thumbnail handler
PDF thumbnails missing	PDF application/thumbnail handler
Preview Pane completely missing	Preview Pane disabled
Preview Pane visible but blank	Preview handler or file security
JPG previews but PDF does not	PDF preview handler
Images preview but Office files do not	Office preview components
Only downloaded files fail to preview	File security/blocking
OneDrive files fail	Cloud file availability/sync
Network files fail but local files work	Network/share/security issue
Problem affects one Windows user only	User profile/cache/configuration
Explorer crashes when selecting files	Shell extension/preview handler

Important Security Note

Thumbnail and preview problems occasionally involve files downloaded from the Internet.

Do not disable Windows security features globally simply to restore previews.

Instead:

• Verify the file source.
• Scan suspicious files.
• Unblock individual files only when trusted.
• Keep Windows and applications updated.
• Avoid unknown codec packs and Explorer modification utilities.

A missing preview is preferable to weakening system security.

Frequently Asked Questions (FAQ)

1. Why are my pictures showing icons instead of thumbnails?

The Always show icons, never thumbnails option may be enabled, thumbnail display may be disabled in Windows performance settings, or the thumbnail cache may be corrupted.

2. How do I enable thumbnails in Windows 11?

Open File Explorer Options → View and make sure Always show icons, never thumbnails is unchecked. Also check System Properties → Advanced → Performance Settings and enable Show thumbnails instead of icons.

3. Does deleting the thumbnail cache delete my photos?

No.

The thumbnail cache contains temporary preview images generated by Windows. Removing it does not delete your original photos, videos or documents.

4. Why is the Preview Pane blank?

Possible causes include a disabled preview handler, unsupported file format, blocked file, damaged file, corrupted application integration or a File Explorer problem.

5. What is the shortcut for the Preview Pane?

On many Windows installations:

Alt + P

toggles the File Explorer Preview Pane.

6. Why can I preview JPG files but not PDF files?

This strongly suggests that File Explorer itself is working and the problem is associated with the PDF preview handler or PDF application.

Update or repair the installed PDF software and check its Explorer integration settings.

7. Why are PDF thumbnails not appearing?

Windows may require compatible PDF thumbnail-handler integration. Check the installed PDF reader, its Explorer thumbnail settings, default PDF application and whether the software needs repair or updating.

8. Why do thumbnails disappear again after I rebuild the cache?

Possible causes include recurring cache corruption, disk-cleanup software, profile problems, insufficient disk space, third-party Explorer extensions or software that repeatedly clears Windows caches.

9. Why do only video thumbnails fail?

The video codec or encoding may not be supported by the installed Windows media components or thumbnail handler.

Test standard MP4 files to determine whether the problem affects all videos or only a specific format.

10. Can OneDrive cause missing thumbnails?

Cloud availability can affect preview behavior. Make a test file fully available locally and check whether its thumbnail appears afterward.

11. Why does the Preview Pane work for some files but not others?

Different file formats can use different preview handlers. A working image preview does not prove that the PDF or Office preview handler is working.

12. Can antivirus software affect Preview Pane functionality?

Security software can sometimes restrict access to suspicious, downloaded or network-based files. However, you should not disable antivirus protection merely to obtain previews. Test trusted files and review the security application's logs or settings instead.

13. Should I edit the Registry to fix thumbnails?

Registry changes are generally unnecessary for normal thumbnail problems. Start with File Explorer settings, cache rebuilding, application repair, SFC and DISM.

Registry editing should be reserved for cases where a specific damaged registration has been identified and a backup is available.

14. Why does Preview Pane say "No preview available"?

The selected format may not have a compatible preview handler, the handler may be damaged, the file may be blocked or corrupted, or the application responsible for previewing that format may not be properly installed.

15. Can a damaged Windows profile cause thumbnail problems?

Yes.

If thumbnails and previews work correctly in another Windows account, the problem is likely associated with settings, cache files or configuration in the original user profile.

16. Will SFC fix thumbnail problems?

SFC can help when corrupted Windows system files are responsible. It will not necessarily repair third-party PDF, media or Office preview handlers.

17. What does DISM /RestoreHealth do?

DISM checks and repairs corruption in the Windows component store used by Windows servicing and system-file repair.

The command is:

DISM /Online /Cleanup-Image /RestoreHealth

18. Why are thumbnails slow to appear after clearing the cache?

This is normal.

Windows must regenerate thumbnails from the original files. Large folders containing thousands of photographs or videos can take time to rebuild.

19. Why do thumbnails work on C: but not on my network drive?

This indicates that the problem may involve the network location, permissions, connection speed, server configuration or security rules rather than the local thumbnail system.

Copy a test file locally to confirm.

20. What should I do if File Explorer crashes when the Preview Pane is enabled?

Disable the Preview Pane temporarily and investigate recently installed or updated applications that provide preview handlers or shell extensions. PDF software, media utilities, cloud clients and Explorer extensions are common areas to investigate.

Conclusion

When Windows thumbnails are not showing or the File Explorer Preview Pane is not working, the problem is usually related to Explorer configuration, thumbnail cache corruption, preview handlers, file security or application integration.

Start with the simplest fixes:

Check thumbnail settings → enable Preview Pane → enable preview handlers → rebuild thumbnail cache → test different file types.

If only one format such as PDF or Word fails, focus on the application and preview handler associated with that format rather than making broad Windows changes.

For system-wide problems, restarting Explorer, resetting File Explorer options, running SFC, running DISM, and testing another Windows account can help isolate and repair deeper Windows problems.

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