Facebook says incorrect password?

First check whether you are inserting your email and password correctly.If caps lock is ON,then off the caps lock option.
But if all inserted/typed correctly then ,Get new password.
Once you click on Forgot Password you will not get your old pass back.You will only get another new pass generated by the facebook support.
So you will have to use that new generated pass.After you login with that new generated pass you can then change your pass back to the old one by going into the settings or profile option.