* Although the crack in the screen is small, it's still possible that it's causing issues with the display. If the crack is near the touch screen, it could be interfering with the iPad's touch sensor. It's also possible that there is some other hardware damage that is causing the issue. If the issue persists after trying the above software fixes, it may be worth taking the iPad to a repair shop to have it checked for hardware damage.
* Before attempting any major fixes or repairs, it's always recommended to backup your data. You can backup your iPad via iCloud or iTunes. Once your data is backed up, you can try to restore your iPad to its factory settings. To do this, go to Settings > General > Reset > Erase All Content and Settings. Note that this will erase all data from the iPad, so make sure to back up everything beforehand.