Site & Admin page blank…now what?

Updated my site today, all seemed fine. I tried a new facebook “Like” code in my custom_functions.php file, saved it, and it seemed to work fine.

When I re-loaded page a minute later, it’s all gone – everything! All pages are blank, even the wp-admin page. What on Earth can I do now? Can’t even log into the site. Can you say “stressed out”??

ANY help would be appreciated! – thanks