What do I do to fix a messed up relationship?

That's really not a lot of information.

Why is the relationship mixed up? Did one of the people cheat? Did one of the people decide they no longer wanted a relationship?

More info is needed.

If you made the things go bad then you can rectify mistakes, if other person done the thing then both of you should talk over it. Communication is very important. Admit you r mistakes and apologise, respect other person's view.