<add key ="Filepath" value="D:\Temp\Test" />

       string strDirectoryPath =ConfigurationManager.AppSettings["Filepath"]; // Retrives the Directory Path

        if (Directory.Exists(strDirectoryPath))
{


     string[] strArrFiles = Directory.GetFiles(strDirectoryPath, "*.txt"); // Gets all the textfile from the Directory path

    if (strArrFiles.Length > 0)
                    {                       
                        
                       label1.Text=strArrFiles.Length + "   File(s) found in the Directory!";
                      
                    }
                    else 
                    {
                        label1.Text="No File(s) in the Directory!";
                    }
}

else
{

    label1.Text = strDirectoryPath +" doesnt Exists";
}