I know that this sounds so obvious but have you checked BIOS to see if the HDD is being recognised?
I would also run some HDD Diagnostic tools over the drive to make sure that it's working correctly. If you don't know the drive makers name you can use the Seatools from Seagate available at
http://tinyurl.com/yvjhu
Or you can use the Ultimate Boot CD available from
http://tinyurl.com/3jnpy
You may need to change the Boot Order in BIOS to boot from the CD drive but it's quite easy to do and if you use the Ultimate Boot CD it has quite a few different Tools available on it to test various things if necessary including the HDD Testing Tools.
Col