If your hard drive can not be recognized by your computer here are some options to try out and reasons behind you not being able to see that drive.
1. The drive has no partition. You should still be able to see the drive letter in Explorer under “My Computer” or “Computer”. If it’s there but you can not see any of the underling data that could be because the partition is corrupt or that the drive has damaged sectors on it. When this is the case you should use either hdd reggenerator or Recover My Files. Both programs cost money.
2. If your computer is not even detecting that you plugged in the hard drive you most likely have a mechanical issue on the drive or it’s not plugged in correctly. Try a known good power and IDE/Sata cable. It’s not uncommon for a sata cable to go bad or for a power cable to go bad. Once you have used known good power sources and connection sources you can cross this off your list.
3. If after step 2 your are still having the issue you should ensure the drive is spinning up. If you hear no noise at all from the drive when you plug it in then the drive is dead. You should at least hear some noise from the drive once you turn it on. Again check with 2. to ensure you have power to the drive. If the drive is in-deed dead. You will most likely need to send the drive off to get the data from it unless you want to attempt to swap out the power board on the drive. This is not too hard to do but at the same time it’s hard because you need to get the exact same power board with the exact same firmware. Not an easy task.
4. If the drive spins up and your computer is not detecting anything and you know you have a known good power source as well as IDE/SATA cable then chances are the drive has a mechanical issue. At this point you most likely will have to send the drive of to get the data back. You can try our Advanced Data Recovery options as well but those tips may not help.