OLEAUT32.dll missing

Whenever we start my friends computer, it keeps on asking for a password. It never asked for password before. It says there is a system file missing called OLEAUT32.dll. Her computer has been possessed for the past few weeks. It couldn't print, copy-paste. It has not been used to connect the Internet, and so I used my USB to try to clean out the viruses before this happened. I used the Avenger to delete this blastclnnn or something from Windows System folder and also something called OLE. Now it asks a reinstallation of the OLEAUT32.dll file and doesn't start Windows. Only the wallpaper can be seen on screen.

The contents of the hard drive are very important that's why we couldn't afford reformatting it. HELP!

 

Backup the contents of the disk (using for example a Linux LiveCD) and then do a repair install of Windows.

 

I'm sorry, I'm not sure how I'm going to do the backup. I haven't done it before, and Windows cannot even start. Is it alright if I reinstall windows without backing it up? Will I lose the contents in the hard drive?

 

I haven't tried repairing Windows. Will try to do that and get back to you. Thanks for the quick reply.

I have one fear though, that Avenger will also block the changes after the repair. What do you think?

Or is there any way I can still do the backup even without being in Windows or Desktop?

 

I haven't mentioned. The computer's OS is XP.