My iPhone is not ring, mute and volumes bottoms not working?

My iPhone 4 (Model A1332), iOS 5.1.1. My iPhone when I get a call won't ring neither vibrate when the ring is on. If I activate the silent mode it will vibrate when a call is received. It has no problem with message tone neither with notifications, it will sound with no problem. Also the mute and both volume bottoms are not responding. doesn't do any thing at all. I have hard reset the phone, I have reprogram the phone with iOS 5.1.1 a few times. I'm not sure if this hapen after update from iOS 4.2 to iOS 5.1 or was that the phone fall off. I have open it and try to reset the connections but the problem remain. Any idea?