Why did the car stop going forwards or reverse

Same problem, do i have to change a motor or the motherboard ?

There's really no way for me to know without more information. If I had to guess, I would guess the motor though. The reason is that the motor is a mechanical part that can wear out, while the circuit board is a solid state part making it less likely to wear out. It could be something else too though. On my rc car(it was just some build your own kit), the brushes on the motor corroded after sitting for a while with the batteries in it.

Thanx Mr Josiah 4 ur response,

if the front wheels r working than no doubt that the prob is not from the motherboard, i ned to change the back-wheels motor.

Not necessarily. There are three general circuits in an rc car. One to receive the signal from the remote which controls the other two circuits, one to drive the rear wheels, and one to turn the front wheels. Each of these circuits have several different components such as capacitors, transistors, and resistors. Many of these components only affect one of the main circuits. The problem could also be in the wires to the motor. Checking the voltage is a sure way to make sure you're changing the right part.

Hopefully all that made sense.