That is kind of tough because you have to be in windows in order to install the USB drivers. The only one available on the Gigabyte site is for the Eltron USB3.0 driver. If you cannot log in to Windows, I am not sure how you can update the driver.
If you have a Windows 8.1 install disk, you may be able to do a Sfc /scannow at the command prompt to repair any corrupted system files. USB2.0 drivers are part of the Windows install disk. You may be able to do a System Restore with the Windows install disk to a previous date but I am not that familiar with Windows 8.
Note: If you have a UEFI bios you should be able to get to the recovery settings. I would try a sfc /scannow at the command prompt first and if that does not work try a System Restore to a date before the problem.
http://www.eightforums.com/tutorials/20256-uefi-firmware-settings-boot-inside-windows-8-a.html This link is not what I wanted. I was hoping to get to recovery options through UEFI , not through Windows as this link suggested.
Edit: Check this link on repairing the computer using the install disk. Middle of page.
Booting to Recovery Environment with Windows 8/8.1 installation media or Recovery Drive/System Repair Disc
Edited by JohnC_21, 19 January 2015 - 06:27 PM.