I read this somewhere. It helped! After checking that the "silence" button is off on side of the phone and the Do Not Disturb is off (in General Settings) Try this:
Settings > General > Accessibility > scroll all the way down to Assistive Touch (click this and turn it on) > a circle appears on the screen - click this > Click on "Device" > check if it shows "Mute" > If Mute is showing click on the Mute bell so that the slash is gone and it says "Unmute"
Once you have "Unmute" showing > click anywhere on the screen to close this menu and click to turn off Assistive Touch
Done
Settings > General > Accessibility > scroll all the way down to Assistive Touch (click this and turn it on) > a circle appears on the screen - click this > Click on "Device" > check if it shows "Mute" > If Mute is showing click on the Mute bell so that the slash is gone and it says "Unmute"
Once you have "Unmute" showing > click anywhere on the screen to close this menu and click to turn off Assistive Touch
Done
