Hello kpmai,
Welcome to Apple Support Communities!
We want to make sure the sound on your iPad is working normally for you.
Try these steps first to check the sound settings:
"Set sound options
Set options for alert tones and ringtones, and ringer and alert volumes.
- Go to Settings
> Sounds. - Drag the slider to set the volume for the ringer and alerts.
- Tap Ringtone and other options to select sounds for the ringtone and alert tones."
Also, try this tip:
"Tip: If you’re not receiving incoming calls and notifications when you expect them, open Control Center, then check whether Do Not Disturb is on. If
is highlighted, tap it to turn off Do Not Disturb. (When Do Not Disturb is on,
also appears in the status bar.)"
This Apple Support page has the full details: Change or turn off iPad sounds - Apple Support
We hope this helps to resolve the sound related issue. Please let us know if you have further questions.
Cheers!