How do I resize my iPad screen back to normal?

If your iPad has a physical defect, you clearly cannot resolve the issue yourself. Your iPad will need to be assessed be assessed by an Apple Technician.

You would be best advised to visit the visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) where the iPad can be assessed. Having had the iPad examined, you will be in the best possible place to explore your available options for remedy:

Genius Bar Reservation and Apple Support Options - Apple

Bigger? Your description as to the nature of your problem is unclear.

You might be best advised to visit the visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to offer assistance:

Genius Bar Reservation and Apple Support Options - Apple