Making Pong in Unity

I am trying to make pong in unity . The problem is that I am not able to Instantiate after deleting the ball. please correct my code scoreboard.cs-

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class scoreboard : MonoBehaviour {
     public GameObject prefabBall;
     public Text scoreP1;
     public Text scoreP2;
     public int P1 = 0;
     public int P2 = 0;
     public GameObject ball;
     public Rigidbody2D rb2D;
     // Use this for initialization
     void Start () {
         ball = GameObject.FindGameObjectWithTag ("ball");
         prefabBall = GetComponent<GameObject> ();
         ball.AddComponent<Rigidbody2D> ();
         if(GameObject.FindGameObjectWithTag ("ball")){
             Debug.Log ("ball found");
         }
     }
     
     // Update is called once per frame
     void Update () {
         GameObject Ball;
         ball = GameObject.FindGameObjectWithTag ("ball");
         if (ball.transform.position.x < -10.6f) {
             P2++;
             Destroy (ball);
             Ball = Instantiate (prefabBall,new Vector2(0f,0f),Quaternion.identity);
             Ball.AddComponent<Ball> ();
         //    Ball.AddComponent<Rigidbody2D> ();
 
         } else if (ball.transform.position.x > 10.6f) {
             P1++;
             Destroy (ball);
             Ball = Instantiate (prefabBall,new Vector2(0f,0f),Quaternion.identity);
             Ball.AddComponent<Ball> ();
         //    Ball.AddComponent<Rigidbody2D> ();
 
         }
         //Instantiate (ball,new Vector2(0f,0f),Quaternion.identity);
 
 
         scoreP2.text = P2.ToString();
         scoreP2.text = P1.ToString ();
         
     }
     /*void OnCollisionEnter2D(Collision2D coll){
         Destroy(ball);
         Debug.Log ("Ball destroyed");
     }*/
 }

ball.cs

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Ball : MonoBehaviour {
     [SerializeField]
     Rigidbody2D rb ;
     [SerializeField]
     float minSpeed = 2f,maxSpeed = 10f;
     float velocity =0;
     int count = 0;
     //for audio
     public AudioSource bip;
     // Use this for initialization
     void Start () {
         rb = GetComponent<Rigidbody2D> ();
         bip = GetComponent<AudioSource> ();
         velocity = Random .Range(minSpeed, maxSpeed);
         float service = Random .Range(0f, 2f);
         Vector2 direction;
         float angle= Mathf.Deg2Rad*0;
         if(service>=1f){
             angle = Random.Range (50, 310);
         }else if (service<1f){
             angle = Random.Range (130, 230);
         }
         direction = new Vector2 (Mathf.Cos (angle*Mathf.Deg2Rad), Mathf.Sin (angle*Mathf.Deg2Rad));
         rb.AddForce (direction * velocity, ForceMode2D.Impulse);
 
     }
     
     // Update is called once per frame
     void Update () {
         
 
 
     }
     void OnCollisionEnter2D(Collision2D col){
         bip.Play ();
             velocity *= 1.03f;
             Debug.Log (transform.position.x);
     
         
     }
 }

Project Link :link text