ConfigurationManager.AppSettings["interfacepath"];
            ConfigurationManager.AppSettings["filepath"];
            bool isModifilepath = false;
            bool isModiinterfacepath = false;
            if (ConfigurationManager.AppSettings["filepath"] != null)
            {
                isModifilepath = true;
            }
            if (ConfigurationManager.AppSettings["interfacepath"] != null)
            {
                isModiinterfacepath = true;
            }
 ConnectionStringSettings connectionStringSettings = new ConnectionStringSettings();
            Configuration configuration =                 ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            if (isModifilepath)
            {
                configuration.AppSettings.Settings.Remove("filepath");
                configuration.AppSettings.Settings.Add("filepath", filepath);
            }
            if (isModiinterfacepath)
            {
                configuration.AppSettings.Settings.Remove("interfacepath");
                configuration.AppSettings.Settings.Add("interfacepath", interfacepath);
            }
            configuration.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");