Lost Login screen

I added a new theme to the wordpress site at http://kobchicago.org. The theme is Themnific. You can look at the demo here: http://demo.themnific.com/. The website it comes from is http://www.simplethemes.org/free/.
I think the theme could be broken and I didn’t notice. Anyway, now when I try to go to the site I cannot find my login screen. Is there any other way that I can log in?
This is not my site. I am working on this site for a non-profit organization. I only have access to one login at http://kobchicago.org/wp-login.php.