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.

After you select Forgot password and enter your username, we offer you recovery options in order to access your account. If you can't access these recovery options, you can click the link at the bottom of the page to verify your identity. You'll then be given a series of questions to verify that you own the account.

To access Gmail on an Android device, download and install the Gmail app from the Google Play Store. Click "Next" after entering your username or email address in the first field after launching the application. Click "Sign in" after filling out the second field with your account password.

Go to the sign in page of the product (for Google Accounts it is myaccount.google.com). Enter your Gmail username (everything that appears before '@gmail.com'). Enter your password.