It is mostly caused by electricity. A surge in electricity can cause a drive to fail. It can also be due to Moisture or humidity. When a device is exposed to such conditions, it can cause commotion and destroy the drive. Another factor that is a reason for the internal hard drive failure is extreme heating. When a device is excessively heated because of no cooling options, or when it is in exposure to a heated area over some time, it damages the drive. This might be one of the reasons for the hard drive not showing up on Mac. Also, to avoid data loss because of such instances, make sure to backup your data beforehand.