The sound on my 11Pro is not working

Thanks, MrBill3. I have gone through those steps and the did not solve the problem.

It is intermittent; meaning that sometimes there will be sound on YouTube, sometimes not; sometimes the phone will 'ring', sometimes not, or sometimes, 1 loud ring and then additional rings that are so low in volume they can very be heard; sometimes I'll be listening with headphones, using the Apple-brand jac, and the sound will cut out. Or my phone will be working, I plug in my headphones and then unplug them, and the phone will no longer ring. It is a bit crazy making. I think you can see why.