Order posts randomly, not by date

$randomPosts = get_posts(array(
   'orderby' => 'rand',
   'posts_per_page' => 5,
   'tag' => $tag,
));

Take a gander at the WP_Query documentation. get_posts uses WP_Query under the hood, so you can use any arguments that may be used there.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)