Instead of my player moving left, right, up, down. How do I make him rotate left and right and move in the direction he is facing?

I’ve recently started getting into game development, I’m making a little simple 2d game. I’ve somewhat worked out character movement after some research but there is a change I would like to make. I just don’t know how.

using UnityEngine;
using System.Collections;

public class Player_Movement : MonoBehaviour {

	Rigidbody2D rbody;
	Animator anim; 

	// Use this for initialization
	void Start () {
	
		rbody = GetComponent<Rigidbody2D> ();
		anim = GetComponent<Animator> ();
	}
	
	// Update is called once per frame
	void Update () {
	
		Vector2 movement_vector = new Vector2(Input.GetAxisRaw("Horizontal"), Input.GetAxisRaw("Vertical"));

		if (movement_vector != Vector2.zero) {
			anim.SetBool("IsWalking", true);
			anim.SetFloat("Input_X", movement_vector.x);
			anim.SetFloat("Input_Y", movement_vector.y);
		} else {
			anim.SetBool("IsWalking", false);
			}

			rbody.MovePosition (rbody.position + movement_vector * Time.deltaTime);
	}
}

Instead of the player simply moving left, right, up, down. I would like him to rotate left and right instead and than instead of simply moving up and down I want him to move in the direction he is facing. Could someone help me with this?

You can use Transform.Rotate to rotate to Vector3.right or -Vector3.left (for right). As for movement, you simply assign transform.forward to the movement_vector variable.