How to restore an iPad without a computer?

no you can't

if you do not own a computer then you need to use the computer of a friend/relative/public library or computer store

connect it by cable toa mac or windows computer (with itunes ) installed and read

If you forgot your iPad passcode - Apple Support

Presumably your iPad indicates that it must be restored:

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

These support pages outline the available methods to restore an iPad - either from a backup, or to Factory Settings:

Restore your iPhone, iPad or iPod touch from a backup – Apple Support

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 Windows PC (with iTunes for Windows 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.

Genius Bar Reservation and Apple Support Options - Apple

i don'n have the chord they gave me the ipat with and i don't have acomputer.now what?

Presumably you have a cable that you use to charge your iPad. This should be adequate to connect your iPad to a Mac or Windows PC.

You need a computer If you forgot your iPad passcode - Apple Support