This is a software problem. Apple hides its head in the sand. The only way they know how to fix it is replace it. Have had problems with sound on all my 3 ipads. And ive fixed them all myself. The headphones one is the worst. First shut off all open apps. Then swipe up until you get the volume icon. Make sure it is grey not black. Then go to settings . Ringtone. You should get sound here.Then go to general.Turn external volume control on and off 5 times or until icon changes to volume, Then reset settings. Leave overnight and it should be fixed. I know this sounds like a lot of mumbo jumbo but it works.