Restore ipad

See >>> If you see the Restore screen on your iPhone, iPad, or iPod touch - Apple Support

Use of a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS) is unavoidable - but the computer doesn’t have to be your own, that of a helpful friend or family member will suffice. Alternatively, the technicians at the Genius Bar of your local Apple Store will be able to assist.

you can't by any means other than using a computer

if you don't have one you can use a computer of a friend/relative/public lib/computer store