I’m not yet sure that this is a permanent solution, but I got my USB ports back real fast a couple days ago and it’s been good since.(And I actually updated-fixed my laptop from only them –not from C:\Windows\WinSxS). I determined that my system had two (2) of these “amd64_usb” sub-folders for each of three (3) ‘Unknown’/missing USB devices, and so I copied these (6) subfolders into my “C:\Downloads\HP Drivers\USB\USB_3.0_eXtensible_Host_Controller_Driver” folder to isolate them for any future possible necessary use.There will be MANY sub-folders to the WinSxS folder -I believe the ones you are most interested in for the USB ports have folder names similar to beginning with “amd64_usb” and include versioning like “” plus either “17238”, “17731”, and/or “18088” for actually up to 3 different ‘Unknown’ or missing USB devices.
Status: The drivers for this device are not installed. Properties: Intel(R) USB 3.0 eXtensible Host Controller - 0100 (Microsoft) Open Control Panel, Device Manager to check for your USB device(s) listed as 'Unknown' under "Other" devices, and take note of the spec's.Workaround/Remedy: Manually reinstall the driver. I believe I have reason to really suspect that the USB drivers (and the reluctance of the manufacturer to advance them for the 8.1 OS…) are really at the root of the problem but, anyway, here’s how I remedied this: I also found that I would lose my USB ports- yet inconsistently so -when either other Windows Updates had been installed or I simply placed a certain microSD plug- w/ its USB adapter -into one of the USB ports (I guess the system couldn’t handle the shock of an 8GB microSD?).
I had the same/similar USB port loss-problem with my HP Pavilion 11-n010dx x360 laptop with Windows 8.1, and I didn’t have the aforementioned problem-Windows Update (or its ‘child’ updates) to begin with.