rotate camera around object with Touch

Hello I am using the Unity "Rotate" script (below) works great on computer but on a touchscreen instead of a picking up where it left off (so I can go continuously around an object) It resets the rotation so I only ever rotate the same part of if Thanks for your help, Here is the script:

 using UnityEngine;
 using System.Collections;
 
 public class rotateCam1 : MonoBehaviour {
 
     public Transform target;
     public float xSpeed = 125.0f;
     public float ySpeed = 50f;
     
     public float  resetTime = 1.0f; //How long to take to reset
     
     private Vector3 startDirection = Vector3.zero; //How far away to orbit
     
     private float x = 0.0f; 
     private float y = 0.0f;
     private float z = 0.0f; 
     
     private Quaternion startRotation;
     private Quaternion rotation;
     
     private bool resetting = false;
     private float resetTimer = 0.0f;
     
     void LateUpdate()
     {
         if (Input.GetMouseButtonDown(0))
         {    startDirection = (transform.position - target.position);
             startRotation = transform.rotation;
             x = 0.0f;
             y = 0.0f;
             z = 0.0f;
         } 
         
         if (Input.GetMouseButton(0))
         {
             x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
             y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;
             z = 0.0f;
             Reorient();
         } 
     }
     
     void Reorient()
     {
         rotation = Quaternion.Euler(y, x, z);
         transform.rotation = rotation * startRotation;
         transform.position = rotation * startDirection + target.position;
     }
 }