What is your ultimate goal? Are you just concerned with retrieving data from the drive? There are options ranging from Linux Live CD to Ultimate Boot CD, to removing the drive and attaching it to another computer to accomplish this.
If on the other hand you want to repair the install then you're going to need the install media (and the correct version, retail, OEM, etc), which is probably getting pretty scarces. If you have the Product Key from the COA on the side of the computer, you might try microsoft, they may help for a small cost for the media and a shipping charge.