using System;

using System.Web;

​

public class Program

{

    public static void Main()

    {

        var encodedUrl = "http://sometestdomain.com/a%20subdirectory/test%20green%20cheese%20purple%20in%20the%20moon.xlsx";

        var unEncodedUrl = "http://sometestdomain.com/a subdirectory/apples peaches pumpkin pie.xlsx";

        var weirdUrl = "http://sometestdomain.com/locations/what/test%2520ra/19-20%2520Property%2520Renew_02062019_063440AM.txt";

        var decodeEncodedUrl = HttpUtility.UrlDecode(encodedUrl);

        var decodeUnencodedUrl = HttpUtility.UrlDecode(unEncodedUrl);

        var decodeWeirdUrl = HttpUtility.UrlDecode(weirdUrl);

        Console.WriteLine(decodeEncodedUrl);

        Console.WriteLine(decodeUnencodedUrl);

        Console.WriteLine(decodeWeirdUrl);

    }

}