PHP 登录过程不起作用

这有什么问题？这是登录进程文件。我得到空白页。

当我输入电子邮件和密码时，此脚本必须在cookie +会话时间中设置登录会话，但由于某种原因，我只得到了空白页。网络上的所有其他文件都运行良好，只是这个文件给我带来了错误。我没有任何错误，只是不起作用。

：/（为我的英语不好而苦恼）

<?php
    ini_set('error_reporting', E_ALL);
    error_reporting(E_ALL);
    require( "./configuration.php" );
    include( "./include.php" );
    $task = htmlspecialchars( $_POST['task'] );
    if ( empty( $task ) )
    {
        $task = htmlspecialchars( $_GET['task'] );
    }
    switch ( $task )
    {
        case "login" :
            $email = htmlspecialchars( $_POST['email'] );
            $password = htmlspecialchars( $_POST['password'] );
            $return = htmlspecialchars( $_POST['return'];
            $rememberme = htmlspecialchars( $_POST['rememberme'] );
            unset( $_SESSION['loginerror'] );
            setcookie( "rememberme", $rememberme, time( ) + 60 * 60 * 24 * 30 );
            if ( !empty( $_SESSION['lockout'] ) && time( ) - 60 * 5 < $_SESSION['lockout'] )
            {
            }
            else if ( !empty( $email ) && !empty( $password ) )
            {
                $numrows = mysql_num_rows(mysql_query( "SELECT `clientid` FROM `client` WHERE `email` = '".$email."' && `password` = '".$password."' && ( `status` = 'Active' || `status` = 'Inactive' )" ));
                if ( $numrows == 1 )
                {
                    $rows = mysql_fetch_array(mysql_query( "SELECT `clientid`, `email`, `firstname`, `lastname` FROM `client` WHERE `email` = '".$email."' && `password` = '".$password."'" ));
                    mysql_query( "UPDATE `client` SET `lastlogin` = NOW(), `lastip` = '".$_SERVER['REMOTE_ADDR']."', `lasthost` = '".gethostbyaddr( $_SERVER['REMOTE_ADDR'] )."' WHERE `clientid` = '".$rows['clientid']."'" );
                    $_SESSION['clientid'] = $rows['clientid'];
                    $_SESSION['clientemail'] = $rows['email'];
                    $_SESSION['clientfirstname'] = $rows['firstname'];
                    $_SESSION['clientlastname'] = $rows['lastname'];
                    if ( $rememberme == "on" )
                    {
                        setcookie( "clientemail", $rows['email'], time( ) + 604800 );
                    }
                    else
                    {
                        setcookie( "clientemail", "", time( ) + 60 * 60 * 24 * 1 );
                    }
                    unset( $_SESSION['loginattempt'] );
                    unset( $_SESSION['lockout'] );
                    if ( !empty( $return ) )
                    {
                        header( "Location:".$return );
                    }
                    else
                    {
                        header( "Location: index.php" );
                    }
                    exit( );
                }
            }
            $_SESSION['loginerror'] = TRUE;
            $_SESSION += "loginattempt";
            if ( 4 < $_SESSION['loginattempt'] )
            {
                $_SESSION['lockout'] = time( );
                $_SESSION['loginattempt'] = 3;
            }
            if ( !empty( $return ) && !empty( $email ) )
            {
                header( "Location: login.php?return=".urlencode( $return )."&email=".urlencode( $email ) );
            }
            else if ( empty( $return ) && !empty( $email ) )
            {
                header( "Location: login.php?email=".urlencode( $email ) );
            }
            else if ( !empty( $return ) && empty( $email ) )
            {
                header( "Location: login.php?return=".urlencode( $return ) );
            }
            else
            {
                header( "Location: login.php" );
            }
            exit( );
            break;
        case "password" :
            $email = $_POST['email'] ;
            unset( $_SESSION['success'] );
            if ( !empty( $_SESSION['lockout'] ) && time( ) - 60 * 5 < $_SESSION['lockout'] )
            {
            }
            else if ( !empty( $email ) )
            {
                $numrows = mysql_num_rows(mysql_query( "SELECT `clientid` FROM `client` WHERE `email` = '".$email."'" ));
                if ( $numrows == 1 )
                {
                    $password = ( 8 );
                    $rows = mysql_fetch_array(mysql_query( "SELECT `clientid`, `email`, `firstname`, `lastname` FROM `client` WHERE `email` = '".$email."'" ));
                    mysql_query( "UPDATE `client` SET `password` = '".$password."' WHERE `clientid` = '".$rows['clientid']."'" );
                    $message = "Your password has been reset to: {$password} 'nIP: ".$_SERVER['REMOTE_ADDR'];
                    include_once( "./includes/class.phpmailer.php" );
                    $mail = new PHPMailer( );
                    $mail->IsMail( );
                    $mail->AddAddress( $rows['email'], $rows['firstname']." ".$rows['lastname'] );
                    $mail->From = $rows['email'];
                    $mail->FromName = SITENAME;
                    $mail->Subject = "Reset Password";
                    $mail->Body = $message;
                    $mail->Send( );
                    unset( $_SESSION['loginattempt'] );
                    unset( $_SESSION['lockout'] );
                    $_SESSION['success'] = "Yes";
                    header( "Location: login.php?task=password" );
                    exit( );
                }
            }
            $_SESSION['success'] = "No";
            $_SESSION += "loginattempt";
            if ( 4 < $_SESSION['loginattempt'] )
            {
                $_SESSION['lockout'] = time( );
                $_SESSION['loginattempt'] = 3;
            }
            header( "Location: login.php?task=password" );
            exit( );
            break;
        case "logout" :
            session_destroy( );
            header( "Location: login.php" );
            exit( );
            break;
    }
    header( "Location: index.php" );
    exit( );
    ?>