“So the first question is, why did the cosigner take the keys? Did you stop making payments and let the financial burden fall on their shoulders? If so, the police aren’t going to do anything.
If that’s the case but you still need access to the car, you can call a locksmith to get a duplicate, or you can contact the dealership and tell them you need a replacement.
If you’ve been making the payments on time and the cosigner took the key, this will turn into a legal dispute. Contact an attorney to see what steps you need to take. Chances are you might have to sue to get the keys returned.”