public static string GetValue(string AppKey)
        {
            try
            {
                string AppKeyValue;
                AppKeyValue = System.Configuration.ConfigurationSettings.AppSettings.Get(AppKey);
                return AppKeyValue;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        public static void SetValue(string AppKey, string AppValue)
        {
            //System.Configuration.ConfigurationSettings.AppSettings.Set(AppKey,AppValue);
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load(System.Windows.Forms.Application.ExecutablePath + ".config");

            XmlNode xNode;
            XmlElement xElem1;
            XmlElement xElem2;
            xNode = xDoc.SelectSingleNode("//appSettings");

            xElem1 = (XmlElement)xNode.SelectSingleNode("//add[@key='" + AppKey + "']");
            if (xElem1 != null) xElem1.SetAttribute("value", AppValue);
            else
            {
                xElem2 = xDoc.CreateElement("add");
                xElem2.SetAttribute("key", AppKey);
                xElem2.SetAttribute("value", AppValue);
                xNode.AppendChild(xElem2);
            }
            xDoc.Save(System.Windows.Forms.Application.ExecutablePath + ".config");
        }