HALP! I was installing the addons for the COWA and my site has gone down - there's no index page showing up??

I have no idea what has or could have been affected so I have no idea how to fix this? I've looked in my backup download of my entire site, but there's no index.php page in the root zencart folder, so I'm at a loos as to why the site now can't find it's index page!!!

www.naturalsoap.com.au

Kathy.