Enter BIOS setup at boot by tapping the F2 key or whatever is given on first boot screen. Is the HD showing up under storage devices? It will have a long model number which if you google it will tell you its make and model.
Download and burn to CD the HD maker's HD Diagnostic
extended CD scan to boot and run. It will confirm its condition.
If it's not listed in BIOS it needs to be replaced. You can return it to HP or replace it yourself. Google for a video on how to remove the HD from your model and then shop for a new one to replace it.
After replacing HD use the Recovery Disks you made or order from HP to recover to factory condition, or get the superior Clean Reinstall - Factory OEM Windows 7.