CrackBerry Genius of Geniuses
If you accidentally checked the Hidden option in the picture's properties, go into the media folder, hit the BB menu and select Explore. Navigate to the folder where your hidden file is (probably somewhere in Media Card>BlackBerry>pictures), hit the BB key again and select Show Hidden (if you don't see the Show Hidden option, there aren't any hidden files in that folder). You'll see all hidden files. If you want to un-hide the pic, highlight it, select Properties and uncheck the Hidden option.
If you don't remember what folder it's in, you'll have to go 'exploring' til you find it.
Posted from my CrackBerry at wapforums.crackberry.com