HELP! MY CAR HAS BEEN REPOSSESSED BUT THEY STILL WANT ME TO PAY THE REMAINDER ON IT, 18 GRAND!! HELP!!!?

I just had my car repossessed and there is 18 grand left to pay on it! i know its my fault for being so stupid and taking on finance but i really need to get out of this mess! they said i can pay in installments but that is going to take years. does anyone know if i can get out of this without going bankrupt? maybe someone who knows the legalities and can suggest something to put to these people?