Not long ago I have been able to recover my 10 year old hacked account aswell.
They basicly will ask you when You've purchased the game, what you're birthday is, you're secret question/answer, and charracter name(s).
But the main thing you will need too recover you're account are the Key Codes from the game itself for them too verify if the name you give matches with the accounts ID.
But if you dont know the email, charracter name or have the game keys.
Then it can prove to be quite difficult for them that you are not a suspected hacker.