link to website not working

Last week I tried to update some plugins and ever since doing this it has been playing up. Usually I can type in the website with www. at the beginning and it works just fine, however now it’s not allowing visitors to access the site with the www. at the beginning. So if you type in http://www.inspiredexplorers.com.au the page just goes blank but if you type in inspiredexplorers.com.au without the www. the page loads as per normal. Can someone please explain how this has happened and how I can fix it? I have already mailed out links with the www. at the beginning so I need to fix this problem asap 🙂
Thanks for your help!