My ZTE ZMAX PRO won't ring for incoming calls.

[AC Question]

I just bought this phone and realized it wasn't ringing anymore. My data is on, airplane mode is off, do not disturb says never and my volume is up. I tried changing the ring tone but you can hear them. It won't even vibrate. If anyone has any suggestions, please let me know because I'm about ready to throw this phone out the door.