Open the BIOS (DEL key or F2 or ? at startup -depends on the computer) and check if it can see your hard drive. If it can't then check the jumpers on the hard drive - you can't have both the hard drive and CD drive both as MASTER. #2 disconnect the CD drive reboot and see if the BIOS and detect the hard drive. IF the BIOS can see the hard drive at this point then change the jumper on the CD drive or connect the CD via a 2nd cable.
Idea #2 most motherboards have 2 IDE plugs - change the cable to the second plug and try to boot to the BIOS