i have iphone4 32gb.
my auto focus also not working.i was tried everthing but not work.
-restore firmware/ios = not working
-install super camera = not working
and lastly i've got the problem solved!
open your default camera application and dont close it.
flick the rear camera using your finger at the top side and the back side of the camera lens,
and that same time too try to tap your screen to help your camera to force/help/make auto focus function to work.
and now your camera + auto focus is working!!