What do i do when my cousin and I took out a loan we never signed any documentation, and now she backed out of the payments. All I have is statement of her making payments before and it stopped and nothing else, no other proof that she had to help me.
If you took out the loan on her behalf (all the paperwork is in your name), then ultimately it's your responsibility to make sure the payments to the bank/FCU/whatever are made. Beyond that, figuring out how to reconcile payments from your cousin is between you and her. Depending on where you live, there may or may not be some type of legal ramifications.
This is why it's generally recommended that if you're going to "loan" money to someone, you either need paperwork between you and them, or should consider it a "gift" in your head when making sure you're ok loaning them the money. There's generally a reason they can't get the loans directly, and you should take that into account as well.