I keep well away from Facebook but usually, if you log in to a site with the wrong password, you're offered to go through the Forgot Password process.
That might involve knowing your e-mail address or the answer to some security question ou set when you opened the account.
Try logging in with any word you want and see if that happens.
Don't give any personal information to anyone outside of Facebook who asks for it to help you. They might just want access to your account.