Account hacked

My gmail account is hacked recently by someone. He changed my password as well as recovery options. He used 2 step verification. Now I have no options to access my account anymore. I tried to access my account several times by my android device. At a stage I found a option which allow to make a verification code to my number. But unfortunately I didn't have my number that moment. Then I found out my number but couldn't reach that number verification again. It was looking for hacker's mobile number. Then i tried several times, now it's not allowing me to go to verification option. What to do?