How do I fix this windows problem

Windows XP home will not boot.
It says that <Windows root>\system32
toskrnl.exe is missing or corrupt. I have my original xp disc. How do I fix this?

You may be able to replace the file.

Scroll down a little.

kb article:

When you boot up rey hitting F8 as soon as the windows logo appears and see if you can goto safe mode.