Hi
Just a thought before you risk losing everything.
When I had a computer seriously damaged, (not bootable) by a virus, I needed to save some documents before I did a clean install.
It is possible to boot from a CD if you have a bootable operating system.
I used a LINUX distribution, KNOPPIX.
I had a KNOPPIX disk that allowed me to boot, and search the drive for files. Save the files to an alternate drive such as a USB thumb drive. Or do what I did and save to an old ZIP drive.
If you have another computer available you can download a Linux Distro.
I am sure there are people more knowledgeable than me on this forum that could give you sound advice on how to do this.
I have found Ubuntu to be an easy Linux system to use. I keep a disk around just in case...
I used it when my HDD died.
Here is a list of various distros:
http://www.livecdlist.com/