This code doesn't need to be updated. You just need to make sure to set the MM_UserGroup value on the login page. Once that is done properly, then this page will work as it did before. 
Thank you sir but below is my login page code. Kindly tell me what I should do
<?php
$Authenticate = new WA_MySQLi_Auth($RMConferenceDBMS);
$Authenticate->Action = "authenticate";
$Authenticate->Trigger = ($_SERVER["REQUEST_METHOD"] === "POST");
$Authenticate->Name = "Administrator";
$Authenticate->Table = "admin_login";
$Authenticate->addFilter("user_name", "=", "s", "".((isset($_POST["user_name"]))?$_POST["user_name"]:"") ."");
$Authenticate->addFilter("password", "=", "s", "".((isset($_POST["password"]))?md5($_POST["password"]):"") ."");
$Authenticate->addFilter("level", "=", "s", "".((isset($_POST["level"]))?$_POST["level"]:"") ."");
$Authenticate->storeResult("user_name", "user_name");
$Authenticate->storeResult("password", "password");
$Authenticate->storeResult("level", "level");
$Authenticate->RememberMe = (false);
$Authenticate->SaveLogin = (true);
$Authenticate->AutoReturn = false;
$SuccessRedirect = "dashboard.php";
$FailedRedirect = "errorlogin.php";
if (function_exists("rel2abs")) $SuccessRedirect = $SuccessRedirect?rel2abs($SuccessRedirect,dirname(__FILE__)):"";
if (function_exists("rel2abs")) $FailedRedirect = $FailedRedirect?rel2abs($FailedRedirect,dirname(__FILE__)):"";
$Authenticate->SuccessRedirect = $SuccessRedirect;
$Authenticate->FailRedirect = $FailedRedirect;
$Authenticate->execute();
?>
