website completely down! Please help

Hello,
This morning I tried to update a plugin and all of a sudden it malfunctioned or something and now my website was unavailable to view. It has been down all day and I have no idea how to get it back up and running. I thought maybe I should do a back up and upgrade to the new WP however even trying to download a plugin to do a backup, it just goes to a completely blank screen and nothing happens.
If I try to go to the website and type in www. at the beginning the same thing happens, a blank screen. However, if I try to go to the website and don’t type in the www. at the beginning it loads ok. The website is http://www.inspiredexplorers.com.au if you want to have a look for yourself and see if you know what is happening.
Please help!
Thanks,