mobile touch button isnt working HELP!

my action button is set to "g" in the pc but when I try to play the game on the phone it wont move what mobile code do I need to add to make this action button works in playing the game in the phone?

how do I add or alter the buttons so they work in the game I see when I changed the unity editor preference to device selected " any android device" the button wont even work on the pc I added the mobile touch code but its still nto working

so whats the universal setting or code I add to make the buttons work on both pc and mobile? please somebody help

it worked fine on the pc in unity

its a android cellphone

 using UnityEngine;
     using System.Collections;
 
     public class hok : MonoBehaviour 
     {
         public float upForce;            //upward force of the "flap"
         public float downForce;
         public float forwardSpeed;        //forward movement speed
         public bool isDead = false;        //has the player collided with a wall?
 
         Animator anim;                    //reference to the animator component
         bool flap = false;                //has the player triggered a "flap"?
 
          
         void Start()
         {
             anim = GetComponent<Animator> ();
              
             GetComponent<Rigidbody2D>().velocity = new Vector2 (forwardSpeed, 0);
         }
 
         void Update()
         {
              
             if (isDead)
                 return;
          
             if (Input.GetKeyDown("g"))
             Touch myTouch = Input.GetTouch(0);
 
         Touch[] myTouches = Input.touches;
         for(int i = 0; i < Input.touchCount; i++)
         {
 
                 flap = true;
         }
         void FixedUpdate()
         {
             if (flap)
             {
                 flap = false;
                 anim.SetTrigger ("Flap");
                 GetComponent<Rigidbody2D> ().velocity = new Vector2 (GetComponent<Rigidbody2D> ().velocity.x, 0);
                 GetComponent<Rigidbody2D> ().AddForce (new Vector2 (0, upForce));
             }
 
             if (Input.GetKeyDown("t"))
             {
                 //...zero out the dog current y velocity before...
                 GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, 0);
                 GetComponent<Rigidbody2D> ().AddForce (new Vector2 (-0, downForce));
             }
         }
 int hit = 0; 
 void OnCollisionEnter2D(Collision2D other)
 {
           if(other.gameObject.tag == "Wall")
     {
         hit++;
         if(hit >= 25)
             Destroy(gameObject);
                }
     if(other.gameObject.tag == "Wall")
     {
                          GetComponent<AudioSource>().Play();
         
     }
 
 }
 }