Why do all Gallery functions return null for me?

Okay, looks like it was my fault, I’ve been playing with shortcodes long time ago and I found out something like this within functions.php:

require_once ('gallery-shortcode.php');

Apparently it replaced the original shortcode and when it happens everything gallery-related breaks / returns nothing 🙂

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