[CarolSEL]

Originally Posted by TheLastSuperman

By that you mean what? That you dropped all tables in the database, deleted all the files then installed 100% from scratch using new files and a clean database and its still not working?

No.
1. My site went down with a server error message.
2. Host got it back up, but home page "wasn't right". I noticed that I had phoney "admins" in my usergroup who were "registered" minutes before the error and deleted them. I read this thread and deleted the install folder. (Obviously, the payload had already been delivered.)
3. Site got hijacked.
4. Via link to ACP I shut down the boards, stopped all plugins.
5. Host restored a web file backup from 2 days prior to hacker reg, ran malware checks; site crashed and I cannot access ACP.
6. Following instructions from this site, I downloaded a fresh copy of 4.2.1 and uploaded the files to the server, overwriting the old ones.
7. Site is still down.

So how do I know if the db is clean? If not, have I lost all the member data? Is there a way to delete all the files except the forum and membership?

I will give this link to host, and will check out all the cleanup suggestions you and Zachary give.