Have you tried a hard reset?
Hold the top or side power/sleep button and the home button at the same time until the Apple logo appears, then release.
Next you might try Reset All Settings.
Reset All Settings
Go to Settings >General >Reset >Reset All Settings. This resets to default everything in Settings, including notifications, alerts, brightness, and clock settings like wake up alarms.
Next would be to restore your iPad as new. Not from a back up.
If none of that works, it may be a hardware issue. Then you would need to take it to the Apple Store or a reputable repair shop.