iPad activation lock

I have started reusing an old iPad that has been in storage for some time. Suddenly the activation lock has been engaged. I can’t remember the password and the email address that it is registered with no longer exists. We won the iPad at a business conference about 6 years ago so I have no proof of purchase - but I can tell you things that are on it like photos etc to prove it’s mine. Can anyone help me get the activation lock removed and reregister the device on my current email. Many thanks for any help.