Top Down Shooter Player Controller

I’ve started to make a top down shooter, and am currently working on a character controller. I’ve created very basic movements, but when I tried to make my character look where the mouse is pointing nothing would happen. I followed the tutorial perfectly, but nothing would work. Could someone look at my code?

public float playerSpeed;
private Rigidbody2D playerRigidbody;

private Vector2 moveInput;
private Vector2 moveVelocity;

private Camera mainCamera;

void Start () {

	playerRigidbody = GetComponent<Rigidbody2D>();
	mainCamera = FindObjectOfType<Camera>();

}

void Update () {

	moveInput = new Vector2 (Input.GetAxisRaw ("Horizontal"), Input.GetAxisRaw ("Vertical"));
	moveVelocity = moveInput * playerSpeed;

	Ray cameraRay = mainCamera.ScreenPointToRay (Input.mousePosition);
	Plane groundPlane = new Plane(Vector3.up, Vector3.zero);
	float rayLength;

	if(groundPlane.Raycast(cameraRay, out rayLength)) {

		Vector3 pointToLook = cameraRay.GetPoint(rayLength);
		Debug.DrawLine(cameraRay.origin, pointToLook, Color.blue);

		transform.LookAt (pointToLook);

	}
}

void FixedUpdate () {

	playerRigidbody.velocity = moveVelocity;

}

}

I have a soultion not sure if it will work, dont use the static float if you not going to use it the right way remove static to see variable in editor but I have the basic mouse things down here you go.
`
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Player3 : MonoBehaviour
{

public static float speed = 1;
private Vector3 mousePosition;

void FixedUpdate()
{
    mousePosition = Input.mousePosition;
    mousePosition = Camera.main.ScreenToWorldPoint(mousePosition);
    transform.position = Vector2.Lerp(transform.position, mousePosition, speed * Time.deltaTime);
}

}`