SAMSUNG Galaxy S3 - no Phone sound?

Hello, I've got an S3 mobile phone. I mainly use text or wifi / Internet. But sometimes people actually call me (voice).

I've got the volume about halfway up, & can hear people if I call. However when people call me, there is no "RING", I only know I've got a missed call. 

Is there an easy way to turn on the "RING" on incoming calls? and a way to STOP it (the ring) going mute after I set it?   

FIXED  - my ring tone was off