Rigid Body Wont transform

I AM Trying To Transfrom A Rigid Body position when it falls of a platform or hit the restart button Help me here is the code that i made

using UnityEngine;
using System.Collections;

public class FallDetact : MonoBehaviour {
	GameObject player;
	// Update is called once per frame
	void start () {
		GameObject.Find ("player");
		}
	void Update () {
		
		if (player.transform.position.y <= -5);	{		
			player.transform.position =new Vector3(0,2,0);
		}
		if(Input.GetKeyDown(KeyCode.R)){
			player.transform.position =new Vector3(0,2,0);
		}
	}
}

but nothing happens… help me

Try to use

void Start () {
player = GameObject.FindGameObjectWithTag("Player");
}

And add tag to player of course