Q: Apple ID locked but it is not an Apple ID

Hello everyone

Exactly two years ago I bought na iPad to my daughter. We set it up, created an Apple ID (based on email in gmail domain), and forgot about it. She used a device but once set-up Apple ID was never re-entered.

Today, during normal use, device asked for activation and requesting entering the Apple ID and password. The password was forgotten. Apple ID was "locked for security reasons".

I was sent to appleid website an it confirms that the Apple ID is locked and sends me to iforgot website. Iforgot website tells me that the Apple ID I enter and is "locked for security reasons" "is not and Apple ID".

I enter my name and email addrress to recover th Apple ID and they do not recognize it. So how come they locked it?

Any ideas?