it wont let me join multiplayer games

I think what you're trying to say is that the "authentication servers are down". If this is the case, this report is a duplicate of MC-207896, which was later resolved as invalid. The reason for this is because, this issue is most likely caused by the use of illegal or incompatible software, which can cause several problems within the game, such as redirecting your login to a random server. In order to fix this issue, I'd recommend reading through the Mojang Notice attached to the parent ticket (MC-207896), and if the problem still persists after following the provided instructions, please contact Community Support as the bug tracker is unable to provide you with assistance.