my 2015 Motorola phone won't ring all of a sudden, even when I push the volume button up to loudest.... it will only vibrate... even the alarm clock cannot be heard...what did I do and how can I undo it ?

How to switch off mute in moto

Check this out: it worked for me and I have a Moto G also.

http://www.ehow.com/how_7158487_unmute-cell-phone.html