Volume Ringer/Buttons no longer functioning

[viper69]

I have never dropped my phone, I have the original OS on it that came with the phone v 5.1

Everything WAS working fine until this morning. The phone rang but the volume was really low for some reason.

NOTE: My metal volume buttons, AND other applications all work fine for raising/lowering volume, be it a game, iTunes music etc.

I went into Settings/General/Sounds

The slider under Ringer/Alerts was set very low (I never changed it). SO I moved back up to so it's loud.

The button "Change with Buttons" is set for ON (as it always has been)

The phone rings loud, BUT IF I press the metal volume - or + buttons on the outside of the case the volume is totally muted, and there is no ringing as the call comes through.

Right after that, I looked inside the software and the slider button has not changed position, it's still set for loud.

What the hell is going on??? I've never seen this, and my phone has been functioning fine w/out any problems.

I turned off the phone and turned it back on...same problem.

Help!