AI car Script problem

I have an problem whit A.I car.

How do I stop the car to drive backwards after a crash and return to its normal position and continue driving on your way?

here is the code:

  var FrontLeftWheel : WheelCollider; 
  var FrontRightWheel : WheelCollider;
 
  var EngineTorque : float = 600.0;
  var waypointContainer : GameObject; 
  private var waypoints : Array; 
  private var currentWaypoint : int = 0;
 
 private var inputSteer : float = 0.0; 
 private var inputTorque : float = 0.0;
 
 function Start () {
 
 rigidbody.centerOfMass.y = -1.5;//-1.5
 
 GetWaypoints(); }
 
 function FixedUpdate() {
 
 rigidbody.drag = rigidbody.velocity.magnitude / 250;
 
 NavigateTowardsWaypoint();
 
 FrontLeftWheel.motorTorque = EngineTorque * inputTorque;
 FrontRightWheel.motorTorque = EngineTorque * inputTorque;
 
 FrontLeftWheel.steerAngle = 20 * inputSteer; 
 FrontRightWheel.steerAngle = 20 * inputSteer;
 
 }
 
 function GetWaypoints () {
 
 var potentialWaypoints : Array = waypointContainer.GetComponentsInChildren(Transform ); waypoints = new Array();
 
 for ( var potentialWaypoint : Transform in potentialWaypoints ) { if ( potentialWaypoint != waypointContainer.transform ) //!= { waypoints[ waypoints.length ] = potentialWaypoint; }
 
 } } 
 

 function NavigateTowardsWaypoint () {
 
 var RelativeWaypointPosition : Vector3 = transform.InverseTransformPoint( Vector3( waypoints[currentWaypoint].position.x, transform.position.y, waypoints[currentWaypoint].position.z ));
 
 inputSteer = RelativeWaypointPosition.x / RelativeWaypointPosition.magnitude;
 
 if ( Mathf.Abs( inputSteer ) <= 0.5 ) //< 0.5 { inputTorque = RelativeWaypointPosition.z / RelativeWaypointPosition.magnitude - Mathf.Abs(inputSteer);//Abs
 
 } else { inputTorque = 0.0; }
 
 if ( RelativeWaypointPosition.magnitude < 15 ) //20 { currentWaypoint ++;
 
 if ( currentWaypoint >= waypoints.length ) { currentWaypoint = 0;
 
 }
 
 }
 
 }