Operating System Fails to Boot

I started up my computer this morning and it did not boot. I get an error on a black screen saying that Windows failed to load because the kernel is missing or corrupt. I tried booting my computer based on last known configuration and also in safe mode but it just does not start up. It keeps giving me the same error message. I wanted to attempt a repair installation but unfortunately i do not have an installation disk. I have a lot of important information on my hard drive and cannot permit losing my data or having my hard drive reformatted during a clean installation. Is there anyway I can repair my operating system without doing a clean installation? I have Windows XP Home Edition installed on my laptop.
