Picture Files There But Won't Show Picture

Hello,

I can't open my picture files anymore. I'm working with Windows XP, and all of a sudden, the pictures won't show up. The file is there, but anytime I try to open it, it says that the preview is not available. Tried opening it in all the picture programs I have, but still won't open. File properties show that the file is still there, I just don't know what to do. Any suggestions? Thanks!