How to Recover your Gmail Account? How can I get back My Hacked Account?

https://www.google.com/accounts/recovery
Write your username in the box then click to "Submit"
Then you can choose following methods to recover your account

1. Answer Security Question:
you remember your security question answer then submit it. If it is correct then you will get options to Reset Password

2. Mobile Verification:
if you use this option Google will send your Password Reset Code on your mobile. Verify it and Reset your Password
(Note: It is applicable only if you had submmited your mobile number in recovery options of your account)

3. Secondary E-mail:
Just go to:
support.google.com/accounts/bin/request.py?hl=en&contact_type=reset_password
Submit your Secondary E-mail id and get Password reset link Via E-mail

Most important is the IP Address.
Submit this form from your personal Pc or Mobile through wich you login mostly.
By Your IP Address Google can identify you that you are real owner of the account.

I hope this will help you to recover your account fastly.