Go to http://accounts.google.com/signin/usernamerecovery and enter any email accounts or phone numbers that you've had for a while and which may have been used as recovery info. The “find your email” page can help you locate any forgotten Google accounts.

On your computer, go to Gmail. Enter your Google Account email or phone number and password. If information is already filled in and you have to sign in to a different account, click Use another account. If you get a page that describes Gmail instead of the sign-in page, at the top right of the page, click Sign in.

If you use Gmail, check the inbox of the recovery email address you provided when you signed up for Gmail. If you didn't provide a recovery email address, you can try another way to recover your account. You'll be asked some questions to confirm it's your account. Answer as best you can.

Another way to find Gmail email address from the desktop website or the official Gmail app is to select your profile image at the top right. If you're on a computer, this shows the email account you're using right now and any other Google accounts you're logged in to in the current browser session.