using System.Collections;
using System.IO;
using System.Web;

public class ListFiles
{
    public static ICollection ListUploadDirectory()
    {
        DirectoryInfo d = new DirectoryInfo(System.Web.HttpContext.Current.Server.MapPath("~/Upload"));//Folder from where you want to retrieve files
        return d.GetFileSystemInfos("*.jpg");//type of files which you want to retrieve
    }

}