I'm getting fatal error while running laravel project php artisan serve

PHP Warning: require(/home/sree/Dev/Websites/PHP/blog/vendor/autoload.php): failed to open stream: No such file or directory in /home/sree/Dev/Websites/PHP/blog/artisan on line 18 PHP Fatal error: require(): Failed opening required '/home/sree/Dev/Websites/PHP/blog/vendor/autoload.php' (include_path='.:/usr/share/php') in /home/sree/Dev/Websites/PHP/blog/artisan on line 18