data not passed between pages in live server

Question

I came across weird problem with my site only after uploaded it to the live server. In localhost I've no issue with these.

The problem is for login and register function. Let me talk about login first.

I keyed in the credentials and found that the page is called in the f12 network tab.However that page doesn't retrieve any data! So I put aside this jquery/ajax for a while and manually checked the php pages if they return any data but still they don't.

Now the flow like this:

login form filled up by user-> ajax request from php script-> php request from class file and return to ajax -> ajax give access to admin dashboard.

Now as I told you, I excluded ajax request and only checked with php and class file. Again it doesn't return anything from the class file to the php script though I only echoed "something"! Its not even go through any function!

Then I omitted, class file, checked the php script with ajax file.I only echo "wexckdsewndxw" and changed tha datatype in ajax to 'text'..still it doesn't get any value!

So in conclusion, data between pages are not passed at all! SO I suspect its something to do with crossDomain issue as mentioned here:

How does Access-Control-Allow-Origin header work?

But not sure how this works and how I should alter my code.

My code for reference:

login-user.js

/*login user*/
  <!--login form submission starts-->
    $("document").ready(function(){
          $("#login-user").submit(function(){             
            var data = {
              "action": "test"
            };

            data = $(this).serialize() + "&" + $.param(data);
            $.ajax({
              type: "POST",
              dataType: "json",
              url: "login-this-user.php",
              data: data,
              success: function(data) {
                  alert(data);
                  console.log(data);
                  var i;
                  for (i = 0; i < data.length; i++)
                  {
                      console.log(data[i].email);
                       console.log(data[i].activate);
                        console.log(data[i].status);

                if($.trim(data[i].status)=='0')
                {
                    //alert("not verified");
                    $('.invalid-popup-link').trigger('click');

                }else 
                {
                    //alert("verified");
                    location.replace("admin/dashboard.php");

                }
                  }//end for

              },
               error: function( jqXhr, textStatus, errorThrown ){
                    console.log( errorThrown );
                }
            });
            return false;
          });
        });
<!--login form submission ends-->

login-this-user.php

<?php
session_start();
include('config.php');
include('class.login.php');

$return = $_POST;
//$return ='{"email":"admin@gmail.com","pass":"admin","action":"test"}';

//$return['json']= json_encode($return);
  //  
  //below code to store in database 
$data = json_decode($return, true);


$login = new checkLogin();
$status = $login->checkLogin2($data["email"],$data["pass"]);
$_SESSION['user_id']=$status;


$login = new checkLogin();
$profile = $login->check_profile($data["email"]);




$activated_id=array();
foreach($profile as $k=>$v){
array_push($activated_id,array("email"=>$v['email'],"activate"=>$v['activate'],"status"=>'0'));
 $_SESSION['email'] = $v['email'];
 $_SESSION['activated_id'] = $v['activate'];

}
//header('Content-Type: application/json');
echo json_encode($activated_id);

  ?>

class

<?php
 session_start();
 ?>
 <?php
 class checkLogin
{
   public $email;
   public $password;
   public $userId;

   public $salt;
   public $hpass;



    public function __construct()
    {

    }

    public function checkLogin2($param1, $param2)
    {
        $this->email=$param1;

        $this->password=$param2;


         $sql = "SELECT * FROM authsessions WHERE  email='{$this->email}'";
        $statement = connection::$pdo->prepare($sql);
        $statement->execute();
        while( $row = $statement->fetch()) {
        $salt=$row['salt'];

        $hashAndSalt=$row['hashpword'];

         $user_id=$row['UUID'];

        }

        if (password_verify($this->password, $hashAndSalt)==true) {
         $status = "verified";
         $_SESSION['user_id'] =$user_id;
         $_SESSION['logged_in']=1;
        }else
        {
        $status = "not verified";
          $_SESSION['user_id'] =0;
         $_SESSION['logged_in']=0;
        }

        return $_SESSION['user_id'] = 1;
    }

    public function check_profile($param)
    {
        $this->email = $param;


        $sql="SELECT * FROM authsessions WHERE email = '{$this->email}'";
        $stmt =connection::$pdo->prepare($sql);
        $stmt->execute();
        $profile=array();


            while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) { 
               $profile[] = $row;
               }
        return $profile;


    }

}
 ?>