How to change keyboard control to touch control ? unity2d

Question

If so, then this code is not mine, since I am still a beginner but trying to create my own game. How to add touch control to a script? I tried to look for other scripts, write my own, but there were always errors or the code did not do what I expected from it. Thanks in advance ;)

 using UnityEngine;
 using System.Collections;

 [RequireComponent(typeof(Rigidbody2D))]

 public class playerMove : MonoBehaviour
 {

    public enum ProjectAxis { onlyX = 0, xAndY = 1 };
    public ProjectAxis projectAxis = ProjectAxis.onlyX;
    public float speed = 150;
    public float addForce = 7;
    public bool lookAtCursor;
    public KeyCode leftButton = KeyCode.A;
    public KeyCode rightButton = KeyCode.D;
    public KeyCode upButton = KeyCode.W;
    public KeyCode downButton = KeyCode.S;
    public KeyCode addForceButton = KeyCode.Space;
    public bool isFacingRight = true;
    private Vector3 direction;
    private float vertical;
    private float horizontal;
    private Rigidbody2D body;
    private float rotationY;
    private bool jump;

    void Start()
    {
        body = GetComponent<Rigidbody2D>();
        body.fixedAngle = true;

        if (projectAxis == ProjectAxis.xAndY)
        {
            body.gravityScale = 0;
            body.drag = 10;
        }
    }

    void OnCollisionStay2D(Collision2D coll)
    {
        if (coll.transform.tag == "Ground")
        {
            body.drag = 10;
            jump = true;
        }
    }

    void OnCollisionExit2D(Collision2D coll)
    {
        if (coll.transform.tag == "Ground")
        {
            body.drag = 0;
            jump = false;
        }
    }