$_SESSION not working with localhost or a webdomine - php

Question

i'm using raw php and using $_SESSION but in every request the $_SESSION is reinstating and all the $_SESSION variables are emptied i used http://127.0.0.1/ insted of http://localhost/ and the $_SESSION work fine but now i update my code to server and the $_SESSION is break again so please any help on and many thnks in advance.
my code
functions.php
function login_user($UserName, $user_role)
{
$_SESSION["UserID"] = get_user_id($UserName, $user_role);
$_SESSION["UserName"] = $UserName;
$_SESSION["UserRole"] = $user_role;
$_SESSION["UserLogged"] = 1;
if($user_role == "s") {
$url = get_home_url() . '/student/student-profile.php';
header("Location: $url");
} else if ($user_role == "i") {
$url = get_home_url() . '/instructor/instructor-profile.php';
header("Location: $url");
} else if ($user_role == "a") {
$url = get_home_url() . '/admin/admin-profile.php';
header("Location: $url");
}
}
login.php
<?php
include ('../autoload.php');
if(!empty($_POST))
{
if(!empty($_POST['username']) &&
!empty($_POST['login_password']) &&
!empty($_POST['user_type']))
{
if(get_user_password($_POST['username'], $_POST['user_type']) == $_POST['login_password'])
{
login_user($_POST['username'], $_POST['user_type']);
} else {
echo 'Password incorrect please try again...';
}
} else {
echo 'Please fill all fields and try again...';
}
} else {
echo 'Some thing went wrong please try again...';
}
student.php
<?php
include ('../autoload.php');
//check if user logged in or not redirect to home page
if(!array_key_exists('UserLogged', $_SESSION)){
$url = get_home_url() . '/home.php';
header("Location: $url");
}
get_header();
echo '<wml>';
echo '<card id="student-profile" title="Student Profile">';
echo '<br/>';
echo '<h2 align="center">Welcome:</h2>';
echo '<h4 align="center">'.$_SESSION['UserName'].'</h4>';
echo '<br/>';
echo '<p align="center">';
echo 'INFO<br/><br/>';
echo '</p>';
echo '</card>';
echo '</wml>';
autoload.php
<?php
include 'helpers/session.php';
include 'helpers/db_functions.php';
include 'helpers/functions.php';
session.php
<?php
SESSION_START();