iPad 2 running on iOS 9.3.5 no sound

Hello, I have an iPad 2 running on iOS 9.3.5 and it was working normally up until about two weeks ago? The volume button works perfectly but instead of the usual volume icon that pops up on the screen indicating what level of sound its currently at, it's replaced with "sound effects" and there are no bars that go up or down when the volume is lowered or raised, and sometimes nothing appears at all. It's really frustrating because I can't watch any videos as the volume is muted unless headphones are plugged in. I believe this is most likely a software issue and I'm really hoping someone has got the answer!