For about the last six months my car's.

For about the last six months my car's electrical components have not been working properly. The odometer, speedometer, headlights, tail lights, radio, etc. Some days, the car will run fine, others, if I hit a bump in the road or even turn on my blinker, something backfires and it all shuts off. When I try to turn it on, it wants to turn over but I think the computer controls the fuel injector and if the system isn't on, the car don't start.

My question is: How do I repair it? What's the estimated price?

Any suggestions would be greatly appreciated!
Thank you.
Ashley