Why cant i get into my account? It says that my account doesnt exist when i log in

I used to play tanki a lot. Then i stopped, now i am playing it again. When i try to log in now with that account, it says the account doesn't exist. But i know it exists because i created a new account and searched the name up to add as a friend and my other account comes up as a third-lieutenant (which is what i was) and i can friend-request him. I cant remember the email i used to create the other account. So how can i get it back? Please help, really want to use it again. The username was BlackPheonix23