|A hard drive connected using USB will not show up in the BIOS. |
What may be wrong is that you have used bad methods of removing the USB drive when done using it.
There should be an icon that appears in the tray be the clock which is used for the safe removal of USB devices. If you disconnect the device before the drive has finished its task you can corrupt the files.
You should see the external enclosure/ cabling that you use to connect the hard drive to the USB ports. Look in Device Manager for that.