Windows Explorer Doesn’t Show Thumbnail Previews in Windows Vista and 7 and server version

Actually its a very common problem in Windows. Sometimes Windows Explorer doesn't show thumbnail previews for images and other files as shown in following screenshot:

It might be due to a bug or the user accidentally turned off thumbnails using Folder Options or System Properties.
Anyway if you are also facing this problem, you can use following easy fix to show thumbnails again in Windows Explorer:
1. Open Windows Explorer, click on Organize button present in command bar and select "Folder and search options".
2. Now go to View tab and make sure "Always show icons, never thumbnails" option is not enabled i.e. its disabled.

If the option is enabled, uncheck the checkbox and click on Apply button.
It should fix the problem. If you can't access Folder Options, you can use following alternative method:
1. Type sysdm.cpl in RUN or Start Menu search box and press Enter. It'll open System Properties.
2. Go to "Advanced" tab and click on "Settings" button in "Performance" section.
3. Now make sure "Show thumbnails instead of icons" option is enabled.

If its not enabled, enable the option and click on Apply button.
That's it. Now you should get thumbnail previews in Windows Explorer without any problem as shown in following screenshot: