when i try to turn on my desktop pc, i receive the following message:

windows could not start because the following file is missing or corrupt:
windows root>\system32\ntoskrnl.exe.
please re-install a copy of the above file.

when i try to do so, it wants a floppy copy, all i have is a cd.

please advise

Microsoft's Windows XP Professional Repair Install step by step
http://www.windowsxpprofessional.windowsreinstall.com/installxpcdrepair/part3.htm

Microsoft's Windows XP Home Repair Install step by step
http://www.windowsxphome.windowsreinstall.com/installxpcdrepair/part3.htm

Vista Repair:
http://www.windowsreinstall.com/winvista/index.htm (index page)
http://vistahomepremium.windowsreinstall.com/repairstartup/repairstartup.htm (guide)

System Restore Vista:
http://www.windowsvista.windowsrein...m/repairsystemrestore/repairsystemrestore.htm

System Restore Xp
http://support.microsoft.com/kb/304449/en-us

But I could guess all day