I believe - your Laravel files/folders should not be placed in root directory.
e.g. If your domain is pointed to public_html
directory then all content should placed in that directory. How ? let me tell you
Open your bootstrap/paths.php and then changed 'public' => __DIR__.'/../public',
into 'public' => __DIR__.'/..',
and finally in index.php,
Change
require __DIR__.'/../bootstrap/autoload.php'; $app = require_once __DIR__.'/../bootstrap/start.php';
into
require __DIR__.'/bootstrap/autoload.php'; $app = require_once __DIR__.'/bootstrap/start.php';
Your Laravel application should work now.