Answer to: Why iPhone 4 doesn't vibrate?Everyone, Before you try the extreme measures listed such as taking the phone apart or going to an Apple store, please try the following. I read it at a few sites and thought it was crazy... but, sure enough, it worked. People said to knock on the back of the phone at the back bottom right of the phone (I guess that's where the vibrator is). Sure enough, I knocked it with my knuckle a few times and it now works. To test, I downloaded the Ibrate app and had it on (wasn't vibrating though iPhone was supposed to). After a couple of good thumps with my knuckle, the phone was suddenly vibrating. Hard to believe? Absolutely. Worth a shot? Definitely.