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 () {
	
	}
}

You can save it by using PlayerPrefs.

For reference see here → Unity - Scripting API: PlayerPrefs

public GUIText showCoins;

void OnTriggerEnter2D(other : Collider2D)
{
if(other.tag=="Coins")
{
coins++;
PlayerPrefs.SetInt("Coins",coins);
}
}
void Update()
{
showCoins.text="Coins" + PlayerPrefs.GetInt("Coins");
}