Well, there are a few possibilities why the car is not responding to the remote control.
The first is that the batteries in the remote are dead. If the batteries are dead, power will not flow to the controls or transmitter. To fix this, you can replace the batteries. For instructions on how to replace the batteries, please see our Remote Batteries Replacement guide.
Another possibility is a loose wire inside the control. The remote works when electricity flows through the control. For the electricity to flow, it needs direct contact between two conductors inside the controller. If the wires are disconnected, you will have to replace the board in the remote. To replace the board, you can go to our Circuit Board Replacement guide.
If you have multiple cars, you can test the remote by using it on the other car. If the other car will work, then the issue is with the car not the remote. In that case you can take a look at the guides for repairing the car.