Hi, 
Perhaps see this information at Account Recovery – Google couldn’t verify that belongs to you.  Also can take a look at this help center topic, Secure a hacked or compromised Google Account.  Both help topics/links will lead you to the Recovery Process.
 
Be sure to read through the entire post and any links from it as well prior to starting the recovery process.  The better prepared you are the better your chances will be for account recovery.
 
Please understand that accounts can not be recovered via this forum and Google does not provide live support for account recovery.  If you are unable to prove your ownership via the recovery process, then the account is lost.