My computer had been running fine til the other day when I went t oturn it on, The computer starts up but after the HP Invent start screen it goes to a black screen that says "No Operating System". I never uninstalled the OS and it should still be on there. I also checked my setup utility and it has my hard drives 1 and 2 as being not installed. How could they have uninstalled themselves and how do i get my computer to recoginize them

Well, this seems like a problem with the connection of the hard drives to the Motherboard. Have you made any recent internal changes? Try to re-seat the cables (unplug and plug in), check power connections, check in the BIOS if they are there, and also check the jumpers. (Sorry for mainly technical lingo, but if you need it explained, just ask)

All the cords an cables are connected securely, the hard drives are not showing up in BIOS, and i haveny made any internal changes since months ago when i installed the second drive. The computer was workin fine intil the other day when the drives stop stopped working.

Have you checked the Jumper settings? How are they configured? Have you had any other issues with the pc? What if you switch the Hard Drives from the primary IDE channel to the Secondary IDE?

Power up, Put the Windows CD in your CD drive, Power down and then restart. You need to find out which drives the BIOS is recognizing. The BIOS should pick up the hard drives even without an operating system installed.

I never got a windows cd when i bought the computer. I'm ordering one though so I can hopefully get it working.