Cause: This is the most common problem with hard drives, and it has a simple solution too. Improper connection of the power cable results in this problem. Also, current-generation drives require more power to run, so if your power supply isn’t powerful enough, the hard drives will fail to start up.
Solution: Check whether the power connector is connected properly; if you think it is, then touch the drive. A powered drive will always vibrate a little because of the high-speed spinning of the platters. If the drive doesn’t seem to vibrate, the platters aren’t spinning, and the drive requires more power to work—in which case, you’ll need to change your power supply. If it is vibrating and still the drive isn’t recognised then probably there is some problem with the data cable connection, or the BIOS is not set up properly.