2D game kit questions with death script and making checkpoints

so i have the 2D game kit and it works for me great how ever i need to get rid/ over ride the death settings but im not sure how as im fully crap at coding i have a checkpoint system that seems to work how ever it gets over ridden by the base death code but im not sure what i need to change to make it stop and only send the player back to the start if they run out of lives

UPDATE on this topic i get 2 errors 1 is NullReferenceException: Object reference not set to an instance of an object PlayerPos.Start () (at Assets/PlayerPos.cs:12)

and 2 is NullReferenceException: Object reference not set to an instance of an object Checkpoint.OnTriggerEnter2D (UnityEngine.Collider2D other) (at Assets/Checkpoint.cs:18)

can anyone help ?

turns out ti was an error with my checkpoint system not the reset of the default system