Phone number
apple id phone number no longer in use and don't remember.
Cant unlock an old device.
iPad mini (6th generation)
Question marked as
Was your ID a mobile number? This support article describes ways to find your Apple ID --> If you forgot your Apple ID email address or phone number - Apple Support
or go directly to this link --> https://iforgot.apple.com/password/verify/appleid#
If you still need help:
Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues."
Contact Apple for help with Apple ID account security - Apple Support