Hi,
First, go into the BIOS and look for an option called "Quiet boot" or Quiet POST" and disable it. Save the settings and reboot. Now it should show everything its doing. Post what it says when it hangs.
The fact that it is not detecting the hard drive suggests it crashed. The CD drive may have also been knocked out of place. Can you boot off a CD like a Windows, Linux, or Memtest86 CD? This may be what is causing it to hang at the POST.