hi I'm trying to reactivated my iPad mini 3 that I forgot my password

If you forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification  email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage            

Apple ID – Forgot Password            

Hi there.

if you forget your passcode, you can try removing your passcode using Recovery Mode. Instructions can be found here: https://support.apple.com/en-us/HT211078