iPad Mini 4 - no sound

I have sound only when earphones are plugged in. The sound volume works for the earphones. If the earphones are not plugged in there is no sound coming from the iPad. I believe there is no mute button on the casing but I cannot see how to get the sound back from the Control Panel

When I adjust the volume using the side buttons I can see (and hear) the volume change but I note it also shows the word "Headphones" above the volume indicator