Get files from directory or folder in ASP.Net

Namespace

using System.Collections;
using System.IO;
using System.Text;

 string[] filePreview = Directory.GetFiles(Server.MapPath("~/Uploads/PreviewFile/"));
                 List<ListItem> filesPreview = new List<ListItem>();
                 foreach (string filePath in filePreview)
                 {
                     DateTime fileCreatedDate = File.GetCreationTime(filePath);
                     filesPreview.Add(new ListItem(Path.GetFileName(filePath), fileCreatedDate.Ticks.ToString()));
                 }
                 GdPreview.DataSource = filesPreview.OrderByDescending(f => Convert.ToInt64(f.Value));
                 GdPreview.DataBind();