Widgets Go Missing and Page Dissapears?

I am trying to help someone with their site that seems to have just gone haywire. They moved a widget off the sidebar and somehow in the process almost all their items from the sidebar dissapeared. I went into their account to look at it and scrolled through the files and when I clicked off the Custom_Function.php file the page went blank, now I can’t access the Dashboard (unless hitting the back button) and her site is completely blank? When I pull it up in IE it says :

The website cannot display the page

HTTP 500

Most likely causes:
•The website is under maintenance.
•The website has a programming error.

She is running the Thesis theme on http://www.CrazyCouponTrain.com

Any ideas or help?