Laravel vendor/autoload.php missing

It's my first time with Laravel. I've install Laravel application via composer but when i try to run artisan command (like: php artisan serve) a fatal error is shown:

Fatal error: require(): Failed opening required 'C:\Apache24\htdocs\app-test\bootstrap/../vendor/autoload.php' (include_path='.;C:\php\pear') in C:\Apache24\htdocs\app-test\bootstrap\autoload.php on line 17

I check in the vendor folder and autoload.php file doesn't exist. I try tu run:

composer update --no-scripts

or

composer install

but nothing is changed.

I use laravel v5.4.30 and PHP7.

Why composer doesn't create autoload.php file in vendor folder?

via Chebli Mohamed