My blue screen problem

I appreciate this is a common problem with various threads already posted, but none them has come to my aid so far, so forgive me for this.

Basically, I got a new anti virus programme from the App Store and it showed that I had that new Backdoor malware thingy on my 2011 Mac. I deleted all the files which the anti virus considered a threat and since then I haven't been able to boot up.

It started with the blue screen. Then I tried the hold shift thing and it got to the plain Snow Leopard wallpaper but I couldn't get anything else to display/work. Then I tried the hold Alt key and that did no better, but it did show me the option to click on the HDD, which I tried.

I have some files I haven't backed up that I'd ideally love to retrieve. Of course, if possible I'd like things to go back exactly to how they were. I have the OS X install DVD but haven't done anything with that so far because I'm in above my head now.

I'm a little panicky at the moment but if the worst come to the worst, I'll just have to heal the wounds with a 2012 Mac that I previously had no intention of buying!

 

I've tried everything I can find on the net. I've reinstalled Snow Lopard and it's still the same. I can see the files in Disc Utility but can't access them. Disc Utility also says there's nothing wrong with my hard drive.

Safe Mode still gives me nothing to work with, just shows me the Snow Leopard wallpaper.

Am I doomed? Is there anywhere other than Apple (I don't have Applecare) I can seek help? Here appears to be a dead end.

I suppose the real embarrassing thing I didn't want to have to admit to is that I never made a Time Machine back up so can't restore, even if that would do any good.