Do I need to get a lawyer if the insurance wont pay for the other party's settlement?

Its been more than 6 months now since the accident. I rear ended a cab with two passengers. The insurance just mailed me today that they wont pay for the settlement. What should I do?! Im just a college student and I dont have $30k! please help! or is there any other way I can work it out with my insurance so that they would pay for it?