Question Healthbar does not slide when damage taken

I followed brackeys tutorial on how to do health bars but when I take damage the bar doesn't go down it just disappears when it reaches zero how do I fix this here are the two codes I used. Help would be greatly appreciated as I am stupid.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5.  
6. public class healthbar : MonoBehaviour
7. {
8.  
9.     public Slider slider;
10.  
11.     public void setmaxhealth(int health)
12.     {
13.         slider.maxValue = health;
14.         slider.value = health;
15.     }
16.  
17.     public void sethealth(int health)
18.     {
19.         slider.value = health;
20.     }
21.  
22. }
23.  

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5.  
6. public class Player : MonoBehaviour
7. {
8.  
9.     public int maxhealth = 100;
10.     public int currenthealth;
11.     public healthbar healthbar;
12.  
13.     // Start is called before the first frame update
14.     void Start()
15.     {
16.         currenthealth = maxhealth;
17.         healthbar.setmaxhealth(maxhealth);
18.     }
19.  
20.     // Update is called once per frame
21.     void Update()
22.     {
23.         if (Input.GetKeyDown(KeyCode.Space))
24.         {
25.             takedamage(20);
26.         }
27.  
28.         void takedamage(int damage)
29.         {
30.             currenthealth -= damage;
31.  
32.             healthbar.setmaxhealth(currenthealth);
33.         }
34.     }
35. }

 

Already answered here https://forum.unity.com/threads/healthbar-does-not-slide-when-damage-is-taken.1240966/