I try to make 2d top down shooting. Everytime i click the mouse button the bullet gets created but addForce doesnt work on it, so it just freezes and only moves if the player touches it.

Questions & Answers
1

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

public class Shooting : MonoBehaviour
{
public Transform firePoint;
public GameObject bullet;

public float bulletForce = 20f;

void Update()
{
    if(Input.GetButtonDown("Fire1"))
    {
        Shoot();
    }
}

void Shoot()
{
    Instantiate(bullet, firePoint.position, firePoint.rotation);
    Rigidbody2D rb = bullet.GetComponent<Rigidbody2D>();
    rb.AddForce(firePoint.up * bulletForce * Time.deltaTime, ForceMode2D.Impulse);
}

}

2

You aren’t calling rb.AddForce on the bullet that you instantiated, but you are instead calling it on the public GameObject bullet; reference in the script…
To make it work again just change your script to :

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

public class Shooting : MonoBehaviour 
{ 
    public Transform firePoint; 
    public GameObject bullet;

    public float bulletForce = 20f;
    void Update()
    {
        if(Input.GetButtonDown("Fire1"))
        {
            Shoot();
        }
    }
    void Shoot()
    {
        GameObject Bullet = Instantiate(bullet, firePoint.position, firePoint.rotation);
        Rigidbody2D rb = Bullet.GetComponent<Rigidbody2D>();
        rb.AddForce(firePoint.up * bulletForce * Time.deltaTime, ForceMode2D.Impulse);
    }
}