you can get a Linux disk called EBCD (emergency boot CD), I have used it a couple of times to rescue a hosed PC, try downloading that, just make the cd, stick it in the mucked up `puter then boot it, it gives you a whole host of tools to mess about with and more importantly allows you look around the hard drive and fix broken files, remove NT/XP passwords, repair the MBR etc.
[EDIT] clicky linky thingy
hic
http://www.ultimatebootcd.com/
free download/use (said that just in case .com worries you)
read the tools description and give it a try, nothing to lose.
Windows: 32 bit extension/graphical shell for a 16bit patch to an 8bit OS originally coded for a 4bit CPU, written by a 2bit company that can't stand 1bit of competition, now available in 64bits.