Laravel – My php index is not redirecting to my dashboard file when I log in

I am writing a login form and do some functions and code about if the password is validated it will redirect to dashboar file.

I chatgpt it but nothing is fix, I hope you help with this kind of problem and learn from it. I am also a beginner in php so bear with me. Thank you!

this is my code in index file

                    session_start();

                    include_once 'config/functions.php';

                    $email = $password = "";
                    $emailErr = $passwordErr = "";

                    if (isset($_POST['submit'])) {
                        $email = filter_input(INPUT_POST, 'email', FILTER_SANITIZE_EMAIL);
                        $password = $_POST['password'];

                        $validation_errors = validate_user_login($email, $password);

                        foreach ($validation_errors as $field => $error) {
                            ${$field . 'Err'} = $error;
                        }

                        if (empty($validation_errors)) {
                            $result = login_user($email, $password);
                            if ($result === true) {
                                redirect('dashboard.php');
                                exit;
                                } 
                        } else {
                            // echo 'something is wrong';
                        }
                    }
                    ?>

this is my functions in function files

function login_user($email, $password) {
    global $conn;

    // Use prepared statement to prevent SQL injection
    $query = "SELECT * FROM users WHERE email = ? LIMIT 1";
    $stmt = mysqli_prepare($conn, $query);

    if ($stmt) {
        mysqli_stmt_bind_param($stmt, "s", $email);

        mysqli_stmt_execute($stmt);

        $result = mysqli_stmt_get_result($stmt);

        if ($row = mysqli_fetch_assoc($result)) {
            // Verify the password
            if (password_verify($password, $row['password'])) {
                // Password is correct
                if ($row['user_type'] == 'users') {
                    session_start();
                    $_SESSION['fname'] = $row['fname'];
                    $_SESSION['user_id'] = $row['user_id']; 
                    // Redirect to the dashboard
                    redirect('../dashboard.php');
                } else {
                    return 'Invalid user type'; 
                }
            } else {
                return 'Invalid email or password'; // Password is incorrect
            }
        } else {
            return 'Invalid email or password'; // User not found
        }

        mysqli_stmt_close($stmt);
    } else {
        die("Error in statement preparation: " . mysqli_error($conn));
    }
}

// Function to handle redirection
function redirect($url) {
    header("Location: $url");
    exit();
}