Website Help Needed

[Judgement]

Randomly my forum went down, and when you try to go to it all you get is a white screen.
No loading bar, nothing.

www.runerevolution.net

Downforeveryoneorjustme says it's on my end.

http://www.downforeveryoneorjustme.com/r...lution.net

However all the members of the forum are also getting this error.
Help?! I'm a new webmaster, and still have loads to learn so sorry if this is a simple problem.

[Peter L]

The site is up, probably got hacked and somebody replaced your index file.

As you can see the other files still work:
http://www.runerevolution.net/memberlist.php

[Judgement]

Yeah that was the problem.
I got the site back up.

Anyways what exploit would someone of used to delete the index.php, so I can patch it?

[BreShiE]

Go and login to the admin panel.

http://www.runerevolution.net/admin/

Delete your current template that you're using and re-upload it. That way it'll be fine, if you need help doing that I'll be happy to help you over AIM.

[D3xus]

Weird error. Does anything exist in your website's FTP server at all?
EDIT: I see that the MyBB Admin panel exists. What happens when you attempt to log into the regular moderator cp?

(thanks to Laugh)

[Peter L]

Dexus don't give inexperienced and ignorant advice.

[D3xus]

Good point :/ updated it to ask for a little more information for the problem.