<form id="login-form" class="text-left" method="post">
                <div class="main-login-form">
                    <div class="login-group">
                        <div class="form-group">
                            <label for="lg_username" class="sr-only">Username</label>
                            <input type="text" class="form-control" id="lg_username" name="username" placeholder="username"
                                   data-container="body" data-toggle="popover" data-placement="left" data-content=""
                                   value="">
                        </div>
                        <div class="form-group">
                            <label for="lg_password" class="sr-only">Password</label>
                            <input type="password" class="form-control" id="lg_password" name="password" placeholder="password"
                                   data-container="body" data-toggle="popover" data-placement="left" data-content="">
                        </div>
                        <div class="form-group login-group-checkbox">
                            <input type="checkbox" id="lg_remember" name="lg_remember">
                            <label for="lg_remember">remember</label>
                        </div>
                    </div>
                    <button type="submit" class="login-button">Submit</button>
                </div>
            </form>

$(document).ready(function () {
        $('#login-form').validate({
    rules: { //rules goes here},
    messages: { //messages goes here},
    submitHandler: submitForm
});

function submitForm(){
            var username = $('#lg_username').val();
            var password = $('#lg_password').val();
            var checkbox = $('#lg_remember').is(":checked");

            var strAjax = "username=" + username + "&password=" + password + "&checkbox=" + checkbox;
            alert(strAjax);
            $.ajax({
                type: 'POST',
                url: 'loginAjax.php',
                data: strAjax,
                cache: false,
                success: function(data) {
                    alert(data);
                    if(data == "1") {
                        window.location.href = "home.php";
                    }
                    else {
                        $("#lg_username").attr("data-content", "Username or password is invalid!");
                        $("#lg_password").attr("data-content", "");
                    }
                }
            });
            return false;
            }

<?php
require_once 'dbcon.php';
session_start();

$username = mysql_real_escape_string($_POST["username"]);
$password = mysql_real_escape_string($_POST["password"]);

$sql = "SELECT * FROM tbl_user WHERE userName = '$username' AND password = '$password'";

$result = mysql_query($sql);
$count = mysql_num_rows($result);
$row = mysql_fetch_array($result);

if($count == 1){
    if($_POST['checkbox'] == TRUE) {
        if(!isset($_COOKIE['name'])) {
            setcookie( 'name', $row['userName'], time() + (86400 * 30) );
        }
    }
    $_SESSION['user_session'] = $row['userName'];
    echo TRUE;
}
else {
    echo FALSE;
}
?>