I have no backups and my data is very important
How could you...lesson learned I would say
(I know... it's sarcastic... but if you have important stuff... back it up!)
Ok, back to your problem:
I had someting like this with a static old site i nearly forgot about... I do not know how... but they got in it via FTP (luckily only a limited account), spammed each folder with tons of HTML pages that where full of pills, porn and poker links. Then they pasted html into my pages that refered to these created pages and external ones... of whcih the links looked pretty much like what I got). It was as if a bot just grabbed every file and pasted links to these files into the code. I guess this is how you push your ranking results in the 3P Business.
Cleaning was ok for me since I only had 3 static pages... have you looked into your database, probably they left that out? what is the content saying? If your DB is ok and only your files where corrupted, backup DB, flush everything, change all passwords of all accesses (FTP, DB, etc). Reinstall CMSMS and upload your backup to the DB...
I hope that you could find some help...
oh... and you should probably notify your hosting provider and report the incident to the police.
Oh dear... the web is like a big city... being smaller... you could park your car unclosed at night at a dark side-alley. But now you carry around a whole garage with you, so your car doesn't get hijacked while you drive on the highway during day.
Best
Nils
that was my fault, now i will be check for updates 
