My name is ***** ***** certified professional with over 10 years experience. I will be glad to assist you with this.
I am sorry to hear that you are having this issue.What is the brand/model of your phone please?
If you have the iPhone, it may be silenced with the ringer switch. The upper left hand corner of the iPhone has two volume buttons and a sliding switch. This sliding switch is the ring/silent switch.The iPhone is in silent mode when the ring/silent switch is in the down position and indicated by a orange circle.Check the ringer/silent button on the side and let me know if it is on or off please.
Okay, This could be a glitch in the software and the iPhone needs to reboot, lets try and force a reboot > Hold the home button and the power button down for about 30 seconds or until the Apple logo appears on the screen, then release both buttons. Then check the ringer. If that fails, go to settings, then go to sounds and try a different ringtone..Also check in Sounds. Under the "Ringer and Alerts" option, make sure that the "Change with Buttons" option is toggled to on. Try using the volume buttons again.
Did the reboot help?