1. Check if the hard drive is properly connected to the computer.
2. Make sure that your hard drive is powered on.
3. Check if the external hard drive can be detected in the Disk Management utility.
4. Make sure you have the right drivers for your device.
5. Consider using recovery software to help identify the presence of the External Hard Drive.
6. Manually update firmware on the external hard drive.
7. Check the disk for errors.