Your account is probably gone, if you do not have any kind of proof of the ownership.
However since the email has changed, as well as probably the IP address, it could be that it would be somehow possibly to recover.
Although i do not believe it is possible.
Im not interested in going the hassle to recover it, I just want it to get it tagged so that whoever hacked it cant use it nor sell it.
What about the address here?
People will find it tough to believe that your account has been hacked, if you cannot sign a message. If both you and the current owner cannot sign a message, it is just your word versus his.