Keyboard not functioning

Key board dead , correct. ? even the caps lock key will not toggle its led.
my guess is you bought a clone keyboard from china, on fleabay
and its dead. as many are, some are wired wrong.
the ribbon cable on mine fits to a special connector that likes to break easy, is your broken this locking jack there?
is it plugged in upside down?
why did you buy a keyboard. was the other dead.
when did the keyboard fail. list week last year, or never
i bought it for cheap with dead kbd....
there is no HP drivers, HP retired this old PC, after 10 years.
so what makes you sure your non HP drivers are any good.?
NO OS stated, not even a clue. XP?
what I'd do , us boot to a Knoppix v7 live boot(dvd/usbstic)(linux)
if the keyboard fails NOW, then its bad KBD. or the jack cable or connector there, (or inserted wrong) or damage. there.
buffer chip is blown up with ESD events. (electrostatic discharges)

is the keyboard dead in BIOS
on ours we hit ESC or F10 and BIOS screens pop
power on hammer ESC or F10 or what the screen tells you to hit.
the go in to BIOS screens, now test the keyboard.
using say the arrow keys to navigate the BIOS menus
if the ESC and F10 key are dead that is a bad keyboard.
what must work here is the electronics.

1. correct keyboard, some clones will never work.
2. cable not damaged
3. cable not upside down
4. connector there not damage the lock not broken,(easy)
5. the MOBO buffer chip not ESD damaged.
6. BINGO BIOS now works by key commands