Calls and contacts
Apps and media
Cause 1 of 2: Silent mode is turned on
When you turn on silent mode, all phone sounds are turned off.
Solution: Turn off silent mode.
Turn silent mode on or off
Slide your finger downwards starting from the top of the screen.
Press the settings icon.
Press the icon next to "Ringtone & notifications" the necessary number of times to turn silent mode on or off.