how to call javascript function from my static webmethod in asp.net c#

[System.Web.Services.WebMethod]
       public static string password(string UserId, string UserName, string Password, string ConPassword, string EmailId, string Country, string date)
       {
           TextBox TxtUserId = new TextBox();
           TextBox TxtPassword = new TextBox();
           //TxtUserId.Text = "";
           //TxtPassword.Text = "";
           string flag = "";
           date = DateTime.Now.ToString("dd/MM/yyyy");
           ScriptManager MyScriptManager = new ScriptManager();
           MyScriptManager = (ScriptManager)HttpContext.Current.Session["Script"];
           Page page1 = HttpContext.Current.CurrentHandler as Page;
           TxtUserId = (TextBox)HttpContext.Current.Session["TxtUserId"];
           TxtPassword = (TextBox)HttpContext.Current.Session["TxtPassword"];
           try
           {
              if (Password.Trim().Replace(" ", "") != ConPassword.Trim().Replace(" ", ""))
               {
                   flag = "false1";
                   //Password.Text = "";
                   return flag;
               }

               else
               {
                   page1.ClientScript.RegisterStartupScript(page1.GetType(), "id", "GetUserIdMessage()", true);     //Message("Hi")  should be printed
                   MyFunctions Functions = new MyFunctions();
                   Functions.insertLogin("insert into UserLogin values('" + UserId.Trim().Replace(" ", "") + "','" + UserName.Trim().Replace(" ", "") + "','" + Password.Trim().Replace(" ", "") + "','" + EmailId.Trim().Replace(" ", "") + "','" + Country.Trim().Replace(" ", "") + "','" + date.Trim().Replace(" ", "") + "')");
                   flag = "true";
                   return flag;
               }
           }

           catch (Exception ex)
           {
            return ex.Message.ToString();
           }
       }