converting standalone code to work on android

hey all.

i am new to scripting and i am making a game for mobile devices. i have made a very basic ladder script with the help of youtube. it works well with a standalone (using up and down arrows to move up and down the ladder) but i would like to put it into an android game so that when you touch a button you can go up it and when you let go of the button you fall back down.

my question is how would i rewrite the script to work with button touch, i have tried using getbuttondown instead of getkeydown but when i do this the character only moves a tiny bit and doesnt go up the ladder at all.

any help would be greatly appreciated :)

this is my script

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

public class Ladder : MonoBehaviour {

 public float speed = 6;
 // Use this for initialization
 void Start () {
     
 }
 
 // Update is called once per frame
 void Update () {
     
 }

 void OnTriggerStay2D(Collider2D other)
 {
     if (other.tag == "Player" && Input.GetKey (KeyCode.UpArrow)) {
         other.GetComponent<Rigidbody2D> ().velocity = new Vector2 (0, speed);
     } else if (other.tag == "Player" && Input.GetKey (KeyCode.DownArrow)) {
         other.GetComponent<Rigidbody2D> ().velocity = new Vector2 (0, -speed);
     } else 
     {
         other.GetComponent<Rigidbody2D> ().velocity = new Vector2 (0, 1);
     }
 }

}