my laravel stop working after i cut and repaste css and view file

my laravel 5.1 suddenly stop working after cut and repaste the css and views folder

it displays this error

Warning: require(C:\xampp\htdocs\yssb\public/../bootstrap/autoload.php): failed to open stream: No such file or directory in C:\xampp\htdocs\yssb\public\index.php on line 22

Fatal error: require(): Failed opening required 'C:\xampp\htdocs\yssb\public/../bootstrap/autoload.php' (include_path='.;C:\xampp\php\PEAR') in C:\xampp\htdocs\yssb\public\index.php on line 22

via Chebli Mohamed