Below are some potential fixes that may resolve this issue on your iOS device.
- Try a soft reset by holding down the Home button and the Sleep/Wake button until the device restarts and you see the Apple logo.
- There’s a side switch on the iPad that can be used for mute. Check in Settings > General and see what is ticked under Use Side Switch To.
- Plug in some headphones and test them and then unplug them again.
- Try going to Settings > General > Reset > Reset All Settings and see if that makes a difference.