Ringtone resets to zero volume automatically. Solution?

[AC Question]

My ring tone volme is always on zero. It won't respond to volume up key. I can slide volume to max and vol down key works but vol up still won't work. When I slide to vol max, press home and then press vol up, vol shows reset to zero. Moved Zedge to device, no solution. This is software, not hardware. What can I do? I see problem threads but no fix. Help!

 

[William Hastings]

Sorry, have galaxy s4 model sm-s975l, android version 4.3