While using RevoUninstaller to uninstall Kasperskiy and some McAfee files (not sure if I had McAfee antivirus, or they were pre-installed) from my PC with Windows 8, I tried to open pictures in My Pictures folder (C:\Users\This PC\Pictures\12345.jpg. Pictures are all folder, and can see them visually as tiles, but they don't open as normally. By default they open with Windows Photo Viewer.

Still I can open them with Paint, Photos, Microsoft Picture Manager, Photo Gallery. I can open PDF, Word, other files; it seems something affected Windows Photo Viewer.

Please provide us certain information to narrow down the issue:

Which version of Photo Viewer is installed on your computer?

Since you are unable to view photo only with Photo Viewer I suggest you to repair Photo viewer and check if the helps.

Follow the steps below:

Press Windows + X and select Control Panel.

Under Programs, select Uninstall a program

Look and double click Windows Live Essential.

Select Repair all Windows Live programs.

Also check if you have any all the latest Windows updates installed on your computer.