website down by possible hacks

hi guys.

I managed my blog site up on the server about 2 weeks ago.
Everything worked out fine till yesterday.

we couldnt access the blog page any more, and even our emails.

a senior officer told me this morning that the hosting company complained that a huge flow of data were running on our site, and breached the server’s security settings. So they blocked our office IP and emails. (I was like …OMG…End of world?)
He also said that other companies on this server got impacted as well.

The plugins I use are Facebook Graph API and Janrain register.

I suspect the following reasons:
1. Janrain does not compatible with our server hosting
2. Virus on local machine got uploaded on server
3. Hacking (the worst)

Im waiting for hosting company to get us a report on what’s going on; and I will disable all of the plugins once we can access the page again.

Im trying my best to calm myself down.

Could anyone share what else I can do?