Go to the Google account recovery page by clicking on the link https //g.co/recover for help and this direct you to the official page of Google. Enter the email address which you want to recover and click on "Next" button.

In https //g.co/recover for Help page, you will be prompted to enter the last password. If you remember then enter the same or else click on the link "Try another way".

Google will ask you series of questions, if you provide the correct answers, then you will get an access to Google Account. If failed, then try another method, i.e. recovery via email and phone number on the same page https //g.co/recover for Help.