The part# for that recovery kit is 5066-0364.
HP no longer supplies them directly, you can probably still find them from 3rd party internet resellers.
Although as old as the computer is you might consider if it's worth putting time into it vs. getting a newer machine.
Myself I would do some tests on the hardware to make sure you don't have a bigger hardware failure before I order any software to fix it. The ultimate boot cd has a bunch of RAM and hard drive tests you could run on it if you choose to try that. http://www.ultimatebootcd.com