Why is collider.enable = true not working in my code?

Question

Working on an asteroid like game, when my ship gets hit it blows up and I Instantiate a new ship and surround it with a shield for a few seconds. While the ship is surrounded by the shield I disable collisions for a few seconds. This all works. After a few seconds I hide shield (SetActive(false)) and then set playerCollider.enabled = true. The shield hides but the collider will not re-enable.

code for when killed

 public void KilledWaitTime()
    {
        SetLivesText();
        Instantiate(player); //respawns player after killed
        shield.SetActive(true);
        playerCollider.enabled = false; //disables collider while shield up.
        Debug.Log("collider = " + playerCollider.name);
        Debug.Log("player = " + player.name);
        Invoke("RemoveShields", 3);
    }

code for removing shield and re-enabling collider

 public void RemoveShields()
    {
        shield.SetActive(false);
       // Collider pc = player.GetComponent<Collider>();
        Debug.Log("collider pc = " + playerCollider.name);
        Debug.Log("player pc = " + player.name);
        playerCollider.enabled = true;

    }

Answer 1

When you call Instantiate(player);, you are creating a completely separate object from the previous player object. When you instantiate the player object, you need to re-assign playerCollider to refer to the collider on the newly created object.

You also may want to keep your player prefab and your current player objects separate:

private GameObject playerPrefab;
private GameObject player;

public void KilledWaitTime()
{
    SetLivesText();
    player = Instantiate(playerPrefab); //respawns player after killed
    playerCollider = player.GetComponent<Collider>();

    shield.SetActive(true);
    playerCollider.enabled = false; //disables collider while shield up.
    Debug.Log("collider = " + playerCollider.name);
    Debug.Log("player = " + player.name);
    Invoke("RemoveShields", 3);
}