well. i built a car everything is ok with the car. but test track doesnt run with that car. what should i do
Are you sure you selected everything? Every part needed? Make sure you click everything again and then try again.
Also, is the test track one of Automations, or you created/modded it by yourself?
Provide us with a bit more info 
yeah i selected everything. i found the problem. if i change tyre types test track doesnt run. and omg. can we create the test track 
Hmm, can you be more specific on the tyre types? What did you do to resolve the issue? What tyres did you have when it didnt work?
And eys, look at Test Track forum to learn how to make them yourself!
I had a similar issue once where a car would run around the Airfield track just fine but if I tried to run it around the Automation test track the car seemed to just stall at the starting line
The problems are very probably only indirectly correlated to the car. It’s more a simulation problem where it doesn’t find the right gear before one corner and the simulation cannot be completed. Because the simulation has to be completed before the animation starts, the car seems to be stalling (the lap time probably shows negative values then). Try changing the gear spacing a little bit, in most cases this will help. It’s just a work-around, but better than nothing.