As described, your iPad may benefit from being restored to factory settings - as this will completely reset your iPad and install a fresh copy of the most recent version of iPadOS (currently iPadOS 15.5).
Before doing so, ensure that you have either a current iCloud or iTunes backup of the iPad - as this will be required to restore your data at the end of the process.
How to back up your iPhone, iPad, and iPod touch - Apple Support
When you are confident that you have a backup of your iPad data, proceed with the Factor Restore:
Restore your iPhone, iPad or iPod to factory settings – Apple Support
Restore all content to iPad from a backup - Apple Support
You’ll need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS).
Download and use iTunes for Windows – Apple Support
Update to the latest version of iTunes – Apple Support
Use of a PC or Mac computer is unavoidable. If you don’t have access to a suitable computer of your own, that of a helpful friend or family member will suffice. Alternatively, the technicians at the Genius Bar of your local Apple Store or Apple Authorised Service Provider (AASP) will be delighted to assist.