Sounds like your "Open With.." got messed up. If you hold down the Shift Key and Right Click on, say, an image. You will see in the list of thing you can do (like Open or Explore) an extra selection called "Open With..."
Clicking on this will open another window which will show all the different programs in your system that you can attempt to have your image file opened by.
Be extra carefull if your fooling around with this function as a wrong choice in the Open With screen will make files open in the wrong program or not open at all.
Glad to hear your System Restore helped you out.
