If you are having issues with sound on iPad, here is how you can get it working. From the iPad home screen:
Step 1: Swipe up from the bottom of the screen to get to the control center.
Step 2: Tap on the bell icon. It is next to the lock icon in the row of icons at the top.
Step 3: Use the sound meter in Control Center to adjust volume as desired, or press the volume up button repeatedly to turn up the iPad’s sound, if needed.
Once unmuted, iPad and iPad Pro will play sound and audio as usual again, at the volume level that the iPad is currently set to.
You can toggle the mute/silent button on and off at any time and for any reason from Control Center, and it works the same on all models of iPad Pro and iPad with any modern iOS release.