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