general problems of the 2004 Nissan Sentra

When my car hit a truck going 25- 30 mph the air bags deployed but not fully. Passenger front hit windshild. Brook windshield. Airbag did not inflation fully on drivers side or passenger side. My car was on a city street. In motion going 25-30 mph.

On 12/08/14, I was driving through I-85 n. At one point I changed a lane towards my left and needed to straighten my car to that lane. But surprisingly the car wouldn't got straightened and steering had no impact/control over the car wheels. As a result my car hit the median of the hwy and after that I was still trying to put it back in the lane. But I had no control on it. It was shaking and speeding up; hit the median with the left middle and again after traveling a few feet hit the median with rear left. At that point both airbags popped out and car changed direction ( from my diagonal left to diagonal right). And it took me to all the way (6 lane)across the other side of the freeway and hit the median on that side again with the front right and straight front. After that the car finally stopped. It was all smoky and the car door wouldn't open. I squeezed myself out through the approx. Six inches opening. I was so scared and still so much depressed that I don't know what to do. I was fortunate enough that I didn't hit anybody or I got hit by any other car or when the car was dragging me to the other side of the highway I didn't go under any trailer. My biggest question is why the steering stopped working and lost control over the wheel? whose fault was this? and finally I got citation from dekalb police for failure to maintain lanes. When I asked the police officer, she told me that I have to prove it that it was a mechanical error. Then the citation will be taken off. There was no check engine sign or anything that I felt unusual. So please take a look into the matter and let me know so that I feel a little better!.