You need to Recreate the thumbnail cache.
We can do so using Command Prompt. Follow the steps below :-
1. Open Start.
2. Search for Command Prompt.
3. Right-click the result and select Run as administrator.
4. Type the following command to stop File Explorer and press Enter:
taskkill /f /im explorer.exe
5. Type the following command to delete all the thumbnail database files without asking for confirmation and press Enter:
del /f /s /q /a %LocalAppData%\Microsoft\Windows\Explorer\thumbcache_*.db
6. Type the following command to start File Explorer and press Enter:
start explorer.exe
7. Close Command Prompt to complete the task.
Now you should be able to browse files and folders on your computer with thumbnail...