About two days ago, my phone stopped vibrating. No matter what I set the vibrate option to, whether I set silent mode on or off, nothing works. I tried restarting my phone, still nothing. I even went to a nandroid backup that was made five days before the problem and yet it persists. I've since gone back to the backup I made before I restored so now everything is in its current, non vibrating state. What do I do?