My newly installed Ubuntu 12.04 gnome-classic just turned into chinese locale after reboot, how do I change it back to English?

I can't find any language menus, and the ones I opened are, well, in chinese...

When I open a terminal and execute gnome-language-selector, I get lots of this in the prompt:

locale: Cannot set LC_MESSAGES to default locale: No such file or directory

locale: Cannot set LC_COLLATE to default locale: No such file or directory

Any ideas?

If I go to the Language section in Users, I only get the options in the picture.