On my macbook air my messages app wont let me sign in yet i have the correct apple id and password, al i get it an unknown error occurred

Hi oof101guy,

The best support article in this instance will be If you can't sign in to your iMessage account or FaceTime on your Mac. There you'll find a step-by-step process on items to check. Work through those options testing after each one to see at which point the matter is resolved. You may also try activating FaceTime as those are very similar services to see if a different error occurs to provide a better explanation of the cause.

Regards.