My idea is to use shock absorbers for RC cars. You can get them in different sizes and qualities. A hobby shop should be able to help you find what will be soft enough. They can be expensive, but many premade are very cheap.
now please anyone tell me how can i make my car pc shock resistant
Basic common sense. The only component that is really sensitive is the hard drive. Don't use suspension systems that allow oscillation, you need damping. Many people use no suspension at all. I prefer stiff rubber grommits on the hard drive mounting. Don't use anything that would inhibit the drive cooling (eg, foam wrapped around the drive).
I've run the same hard drive for over four years on the rubber grommit suspension with no problems whatsoever.