Coins store problem !!!

Can anyone please help me with this ? My coins are deleting after i restart the game or I die ... How can I save them ?

Here is my code:

 using UnityEngine;
 using System.Collections;
 
 public class Coins : MonoBehaviour {
 
     private uint coins = 0;
     public Texture2D coinIconTexture;
 
     // Use this for initialization
     void Start () {
     
     }
 
     void CollectCoin(Collider2D coinCollider)
     {
         coins++;
         
         Destroy(coinCollider.gameObject);
     }
 
     void OnTriggerEnter2D(Collider2D collider)
     {
         if (collider.gameObject.CompareTag("Coins"))
             CollectCoin(collider);
     }
 
     void DisplayCoinsCount()
     {
         Rect coinIconRect = new Rect(10, 10, 32, 32);
         GUI.DrawTexture(coinIconRect, coinIconTexture);                         
         
         GUIStyle style = new GUIStyle();
         style.fontSize = 30;
         style.fontStyle = FontStyle.Bold;
         style.normal.textColor = Color.yellow;
         
         Rect labelRect = new Rect(coinIconRect.xMax, coinIconRect.y, 60, 32);
         GUI.Label(labelRect, coins.ToString(), style);
     }
 
     void OnGUI()
     {
         DisplayCoinsCount();
     }
     
     
     // Update is called once per frame
     void Update () {
     
     }
 }