DragDrop.cs

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

public class DragDrop : MonoBehaviour, IPointerDownHandler, IBeginDragHandler, IEndDragHandler, IDragHandler
{
    [SerializeField] private Canvas canvas;

    private RectTransform rectTransform;
    private CanvasGroup canvasGroup;
    public int objectNum;

    // Store the original position of the item
    private Vector2 originalPosition;

    private void Awake()
    {
        rectTransform = GetComponent<RectTransform>();
        canvasGroup = GetComponent<CanvasGroup>();
    }

    private void Start()
    {


        // Store the original position at the start
        originalPosition = rectTransform.anchoredPosition;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        Debug.Log("OnBeginDrag");
        canvasGroup.alpha = .6f;
        canvasGroup.blocksRaycasts = false;
    }

    public void OnDrag(PointerEventData eventData)
    {
        rectTransform.anchoredPosition += eventData.delta / canvas.scaleFactor;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        Debug.Log("OnEndDrag");
        canvasGroup.alpha = 1f;
        canvasGroup.blocksRaycasts = true;
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        Debug.Log("OnPointerDown");
    }

    // Method to reset the item to its original position
    public void ResetPosition()
    {
        rectTransform.anchoredPosition = originalPosition;
    }
}