Phone won't ring but will occasionally vibrate

My problem has gotten worse over time but pretty much not working at all now. At first phone would vibrate but not ring...checked all the mute buttons and suggestions on the Internet...also reset the phone. Now doesn't seem to ring at all when testing it and no missed call notification. My brother tapped on the back while testing the ring and a couple of times it would kick in so I'm thinking a loose connection somewhere....any suggestions on how to fixit? Thanks!