My xbox 360 minecraft will not let me play multiplayer?

I don't play minecraft, but if you mean you can't play online multiplayer, then make sure you have a live gold membership, otherwise you can't play online, I'm not sure what you totally mean.

Doing? Doesn't give anyone any details, it could be hundreds of things, what does it say/do when you go in multiplayer?

You might have to update your xbox or minecraft, or both. Make sure your gold membership hasn't expired

Sorry… "?" does not tell me anything about the problem, therefore I can't help you. Try updating the question with some detail.