iPad has been compromised

While at Edinburgh airport my iPad switch language from English to German and my passcode no longer worked.

I reset the device with iTunes but after resetting it does not recognise my Apple ID as the owner but some p*****@gmail.com.

Possibly the device was hacked and someone uses the Apple ID pirate**@gmail***.

Note I have 2 iPad airs so I don't know if I chose the right one in the selection that follows.

Do you have any advice?

Thanks

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