Glad to hear K/B works in BIOS.
Did you try an USB K/B?
Another workaround is to use F8 to access safe mode when you get a K/B that works, and choose Administrator. Most of the time, Admin does not have a password, just hit enter, and you are in.
Follow DonZ63's advice and repair using driver reinstall via device manager.
Failing that, go here for a copy of the keyboard driver you need and paste into the system folder using linux: WINDOWS\Service Pack Files\i386
There are three files on my XP system:
Only two of the files actually go into the WINDOWS\System32 folder:
I do not know what files there should be on Vista, however. An .inf file is actually an installation file for the driver, so... (Using this .inf file may take care of having to register these files as merely copying and pasting the needed files may not work. Double-clicking the .inf file should get it to run.)
I have not done this before, so am not sure if this is a needed step.
I do not recommend searching on the internet for a copy of the file(s) you may need, as some are not clean, depending on the reputation and integrity of the site you are visiting.