The guardrail that ruined my life

A few years ago, my son had an accident - in my car. I was asleep at the time.  I always kept the keys in the bookcase. He took out a guardrail and totaled my car. The insurance wouldn't pay for it, and he received a bill for $2, 500 and something. I didn't think much of it until last fall when he and I received a law suit for nearly $30, 000 - 10 times the original amount!!!!! I don't know how this happened.  I wrote a response and filed it with the court.
Two months later, we received a judgment - we never even heard anything about a hearing!
I contacted the department of transportation, and all they will say is that the accident took place. I know that, but a guardrail does not cost $30,000 to repair according to my research.
Does anybody know anything about this problem? Can anybody help? I'm disabled with a very limited monthly stipend, and my son will probably be disabled soon, too.

Any ideas?