NTLDR Missing?

Hey.. Whenever I load up my computer, it won't go past the first few screens. It gives an error saying NTLDR is missing. I han't a clue on how to fix it.. I don't wanna have to reformat 'cos I don't have all my stuff saved. I've got Win XP btw and this prob just sort of popped up over night, quite literally. It were fine that night, then in the morning it wouldn't work... Anyway.. Any ideas?

you need to go through thish article:
http://www.computerhope.com/issues/ch000465.htm

Actually I got it fixed:

I was told to reinstall windows again over my old one, thus replacing any missing files. This kinda worked, every time I booted up the same error came up. So, I just saved all my stuff that I needed and reformatted 😉

Working okay now.. Thanks for the link though. Will check it out so I know what to do if the problem occurs again.