Roughly 30 Million accounts were hacked on Facebook. There are step so you can find out whether or not your account was hacked.
You have to log into Facebook first and go to the help center.
You can find the link for the HELP CENTER here.
Scroll all the way to the bottom and you'll see "Is my Facebook account impacted by this security issue?"
If you are logged into your facebook account, you should receive an immediate message in the box.