Very sorry to hear you are having problem, first step would be to read over some of the threads here:

http://www.lunarforums.com/lunarpages_security_center-b34.0/

You'll find lot of good advice there. 

also follow some of the suggestions here:

http://wiki.lunarpages.com/Web_Site_Security_Breaches

To start things out, be sure also to do a clean sweep on your computer and any other computer you have worked on this site with.  I would suggest:

1 online anti-virus scanner (full scan)
1 installed anti-virus scanner (full scan)
1 or more anti-spyware or anti-malware programs

You can find suggestions for those here:

http://www.lunarforums.com/lunarpages_security_center/free_antivirus_and_antispyware_programs-t53253.0.html

Once you are sure your PC is clean, then you need to start looking at your web site files, and seeing if any have been changed - or if new files or folder have been inserted.  Also be sure to check system files like the .htaccess file for injected information.

Check file and folder permissions too, in most cases the highest files should be set for is 644 and folder 755.

If you have any installed scripts (no matter if you installed them and you are using them, or you installed them once, decided against using it and never messed with it again) be sure they are up to date with the latest version released from the script creator's official site.

Hope that helps to get you started!

You could restore your information from a backup (might contact support@lunarpages.com for more help with that) however, you might also want to take the steps above to make sure that you are not infected in any way, which in turn would just re-infect your web site as soon as you got it restored.

There are several ways to back up a database for WordPress.  Here's one from their official site:

http://codex.wordpress.org/Backing_Up_Your_Database

and also, there are more than a few plugins that might help too:

* http://wordpress.org/extend/plugins/search.php?q=database+backup