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 the next page, you'll be asked for your name.

If you need to locate the username of a Gmail contact, you can run a search by phone number. You can access this search feature by clicking "Gmail" on your Gmail page and selecting "Contacts" from the drop-down menu.

On your computer, go to gmail.com. Enter your Google Account email address or phone number and password.

On your computer, sign in to Google. On the top right, select your profile image or initial. On the menu, choose Add account. Follow the instructions to sign in to the account you want to use.