cant log into my account

I havent logged into my aternos acc in a few months. I use to be automatically logged in but since i havent been on the site recently i had to relog in. I had my password saved in googles password manager so i tried to log in using that. But it keeps on saying that the username doesnt exist. I changed my username a while ago but it didnt stop the account from working at the time? I dont think I attached an email to the account so i have no way of logging back in. Any suggestions on what to do?