If your HDD is not being detected by your portable system trouble shooting is fairly direct:
- Remove and re-seat the hard drive to ensure the connection to the system is effective, sometimes there is enough play that over time the connection loses contact due to thermal expansion/contraction and re-seating the drive resolves.
- Reset the BIOS default settings. This can be done from within the BIOS (F2 at boot for most systems, F1, F10 and DEL are the other most common entry prompts, watch you screen at boot for BIOS/SETUP access prompts if unsure) Check the Hard Drive Controller Settings/SATA controller settings and write them down, and once you reset the BIOS defaults, check them again. If they have changed, set the controller setting back to the pre-reset setting to avoid 0x0000007B controller errors on reboot. Most Phoenix brand bios can be reset by pressing F9, Enter. Others will have a maintenance section where default settings can be restored. After resetting, save changes and exit this will force re-numeration of all devices by the system, including the hard disk drive. If using a desktop chassis and you have multiple controllers, swap cables with a know working controller (Usually the Optical drive) and see if the drive is detected on that cable and controller and the optical drive on the HDD controller.
- If the Hard Drive is still not detected, you can remove the hard drive and install it in a USB external drive case and see if the drive is detected on another system. If it is not, then the drive has failed, and needs replacement. If the drive works in the USB adapter then the controller is suspect on the system the drive was removed from, and a motherboard replacement is likely the end result.