no volume with calls coming in, fixed

for some reason i couldn't hear calls coming in.  it would vibrate, but if the phone wasn't next to me i never heard it ring.

went to every setting on the menu, couldn't figure it out.

searched this forum, couldn't figure it out.  everything else pointed to full volume setting.

accidently discovered that when i called myself, and the phone was ringing, if i hit the volume button on the side it increased the volume.

hope that helps someone sometime.