What do i do if i lost my car ownership before i was able to put it in my name and also now i can' get a hold of the guy that i purchased it from what should i do?

What do i do if i lost my car ownership before i was able to put it in my name and also now i can' get a hold of the guy that i purchased it from what should i do?
Hello i have a question? I lost my car ownership and i don't know how can i get an other one? I need to donate my car to cancer society...