A few days ago, my iPhone stopped vibrating. When I silence the phone or when I have the ringtone on. It used to vibrate when I moved the button to silence as well, but no longer. And when I used to move the silence button the screen would light up and show the bell with the slash through it to let me know it was silent. but it doesn't do that either. It only shows that if the phone is backlit. Would a software restore fix this or is there a greater problem?