If you’re unable to get into your Facebook account, hackers may have already changed your account’s email or phone number.
At this point, you’re essentially locked out and it will be much more cumbersome to recover hacked facebook account.

Even though Facebook’s official account recovery process is readily available online, many victims of aggressive Facebook account hackers have a hard time getting their accounts back.
Open Facebook on all of your devices
If you’re usually logged in to Facebook on multiple devices, open your Facebook app or webpage on all of your devices and see if any of them are still logged in.
Find your account
First, make sure to start the process on a computer or mobile device that you typically use to access your Facebook account.
Change the email address connected to your Facebook account
If the system is able to locate your account, it will ask to send a verification code to the address or phone number currently associated with the account. If the account or phone number listed do not belong to you, select No longer have access to these, and Cannot access my email.
Set up a recovery email address
Once you finally gain access to your account, go straight into your Settings & Privacy menu. Choose Settings, then General.