Hello @Rob hope you’re fine. 
There is a problem with spaceship, player in the game, it just not moving neither left or right. There is no error in the script i checked.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlayerController : MonoBehaviour {
public float speed = 15.0f;
public float padding = 1f;
float xmin;
float xmax;
void start (){
float distance = transform.position.z - Camera.main.transform.position.z;
Vector3 leftmost = Camera.main.ViewportToWorldPoint(new Vector3(0,0,distance));
Vector3 rightmost = Camera.main.ViewportToWorldPoint(new Vector3(1,0,distance));
xmin = leftmost.x + padding;
xmax = rightmost.x - padding;
}
void Update () {
if (Input.GetKey(KeyCode.LeftArrow)){
//transform.position += new Vector3(-speed *Time.deltaTime, 0 , 0);
transform.position += Vector3.left * speed * Time.deltaTime;
}else if (Input.GetKey(KeyCode.RightArrow)){
//transform.position += new Vector3(speed *Time.deltaTime, 0 , 0);
transform.position += Vector3.right * speed * Time.deltaTime;
}
// restrict the player to the gamespace
float newX = Mathf.Clamp(transform.position.x, xmin, xmax);
transform.position = new Vector3(newX, transform.position.y, transform.position.z);
}
}
. But then i fixed it. As my laptop broke down and i will not be able to continue this course until it get fixed.