So all i need to do is sign a message from 1 of my previous address that i used and send it to you ?
No. To an admin. Only they can reset passwords or change emails.
What happens if i never signed a message before ? Can i just sign it now from one of the addresses i used?
As long as there's an address connected to that account such as bitcoin address you posted, have transaction from where you can sign a message then you can hopefully recover your account.
Recovering accounts mostly take months. Anyway, lemme check your account to see addresses that is connected to it.