Help with jumping

I’m making a test game (this is my first experience with unity) and I am attempting to make my character jump. I am getting this code from a tutorial video by the way, and I can move from right to left just fine, but my player will not jump, please help.
Code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour
{
    public Rigidbody2D rb;

   
    public float speed;
    public float jumpForce;
    private float moveInput;
    private bool facingRight = true;
    private bool isGrounded;
    public Transform groundCheck;
    public float checkRadius;
    public LayerMask whatIsGround;
    private int extraJumps;
    public int extraJumpsValue;
    void Start()
    {
        extraJumps = extraJumpsValue;
        rb = GetComponent<Rigidbody2D>();
    }
    void FixedUpdate()
    {
        isGrounded = Physics2D.OverlapCircle(groundCheck.position, checkRadius, whatIsGround);
        moveInput = Input.GetAxis("Horizontal");
        rb.velocity = new Vector2(moveInput * speed, rb.velocity.y);
        if(!facingRight && moveInput > 0)
        {
            Flip();

        }
        else if(facingRight && moveInput < 0)
        {
            Flip();
        }
    }
    void update()
    {
        if(isGrounded)
        {
            extraJumps = extraJumpsValue;
        }
       
        if(Input.GetKeyDown(KeyCode.UpArrow) && extraJumps > 0)
        {
            rb.velocity = Vector2.up * jumpForce;
            extraJumps--;
           
           

        }
        else if(Input.GetKeyDown(KeyCode.UpArrow) && extraJumps == 0 && isGrounded)
        {
            rb.velocity = Vector2.up * jumpForce;
        }
       
    }
    void Flip()
    {
        facingRight = !facingRight;
        Vector3 Scaler = transform.localScale;
        Scaler.x *= -1;
        transform.localScale = Scaler;
    }
}

images:


bump

nvm I’m dumb just for got to make the u in update capital