error cs0103 unity the name text does not exist in the current context and same for the button what can i do plz someone help Asap

using UnityEngine; using System.Collections;

public class GameplayController : MonoBehaviour { public static GameplayController instance;

 [SerializeField]
 private Text scoreText;
 [SerializeField]
 private Text endScore;
 [SerializeField]
 private Text BestScore;
 [SerializeField]
 private Text gameOvertext;
 [SerializeField]
 private button d;

 private  
 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
 
 }

} heres the complete code.