here you are the soultion works with me:
public string GetHtmlFromUrl(string url)
{
string html = "";
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
html = reader.ReadToEnd();
reader.Close();
response.Close();
return html;
}