If you lose your password for your Google account or if someone steals your password and hacks your account, you will need to recover your account. Open the Google account recovery page and attempt to answer the security questions there.
If you entered a recovery email account or recovery phone number with your Google account before the hack occurred, you should have a better chance of completing this step successfully.
Once you regain access to your account, you will want to change and strengthen your password and enact other forms of security, such as two-factor authentication, to protect your account.