Help to stop Bulk mail sent out from my site

My site was suspended by the host due to a bulk mail sent out via my account and hundreds of Ads post to my Blog page couple of days ago. I was asked to clean up scripts to fix the problem by host to reopen my site. But I don't know where to start, compare all files installed with backup ones or something else. The site is running D7.0.8.

Any helps are very welcome.

Thanks.

What kind of bulk mail - like if you were sending a broadcast message from the site?  Have you installed and uninstalled modules several times by any chance?  I had to get the help of Boonex to fix mine when it was doing this.  It turns out modules don't always uninstall correctly, and the leftover code can cause this.

If you post a question and someone responds and then you re-post the same question the next day without checking the original post it  makes it hard on the person who is trying to help narrow down what's wrong. Check and see if the "matching" system is turned on or off in admin. Also if your blogs are full of ads that means your site is probably full of spam accounts. Have you deleted all the accounts that posted the ad blogs? There are some ideas on blocking the spammers here:

http://www.boonex.com/forums/?action=goto&search=1#topic/spam-spam-spam-spam-IDEA-.htm

Thanks.

Arvixe allow only my PC to access my site, so I can log into admin panel.

I checked my site from admin and it seems that the bulk email and Ad blog post not from the site members

but from outside spammer.

Someone who isn't a member of your site at all is able to post to the blogs? What is the username that the blog post shows? Could it be a member that you deleted?