A couple of months ago my great little pocket camera (Sony DSC-W150) malfunctioned after I dropped it. When I turned it on, the lens would go in and out for a couple of minutes, and then it would give me the message "Turn camera off and then on again." Turning it off and on just led to the same thing all over. I've come to feel that I must have a camera with me at all times, so I ran out and bought another one (Sony DSC_S980), which is nowhere near as good as the broken one, but a lot cheaper. I really missed my good camera. The new one sorta sucks, really. It's slow to focus, slow to cycle, not as good in low light, doesn't give me nearly as much control in manual mode and it has a Sony lens, which is noticeably not as good as the Carl Zeiss lens on the W150.
The other day I decided to see if the Google could help me figure out how to fix the old one. Turns out the problem is very common: the lens, which extends when the camera is turned on, can get very slightly out of alignment if the camera is dropped. But the solution that seemed to work like a charm for everyone is: drop it again. Or maybe not drop it; most people had success just rapping it solidly against a table or a countertop. I was a little trepidatious about slamming my favorite camera around on purpose, but then I figured, hell, it doesn't work anyway. So I gave it a quick medium-hard slam ... and whaddya know, the damn thing works again.
This makes me very happy.