Air Bag On-off Switch problems of the 2009 Ford Focus

Air bag light is stuck on randomly makes a "dinging" sound. Tires continue to wear out at a rapid speed, ignition switch will get stuck an engine will not turn over-can't find a cause. And the a/c stopped working this week, mechanic looking for a leak unable to figure out these issues and why they all started with in past month. Each problem they can't find solutions or tell me it's probably a sensor or the heat. They hook it up to the computer and it shows nothing wrong?!?!.

I was involved in a rollover in 2009. The car steering was loose and caused me to lose control on the road. I was switching lanes on the highway, the road was uneven and the steering seemed to stop working. Also the airbags did not deploy. It was a rental car.