F:\xampp\htdocs>php artisan serve
Could not open input file: artisan

It’s very simple. You are trying from root. Just go to your project with following command

F:\xampp\htdocs>cd laravel

then try

F:\xampp\htdocs\laravel>php artisan server

F:\xampp\htdocs\laravel>php artisan serve
Laravel development server started on http://localhost:8000/