Long-time subscriber and friend Ed Walker wrote me about a problem he’d observed a couple times recently at work — and the solution, too.
I can see how this can happen. I hope Ed’s article can help other readers…
"My USB ports don’t work any more"
This problem has occurred here at work twice in as many weeks. The system failed to display or make available any device plugged in to the USB drive, even though the device showed under computer management. In both cases the error was created by mapping network drives. Coincidentally, both errors involved mapping a network drive and assigning the drive letter of E: to the networked drive.
Any storage device connected to a USB port is assigned the next available drive letter in the local machine. In these two problem cases the next drive letter available locally was “E:”, but E: had already been assigned to a mapped network drive. The USB drive was not accessible.
The fix was to release the mapped drive (E:) and do a ‘Safe Remove’ of the USB drive. Re-connecting the USB drive provided the desired results.
TIP: When mapping a network drive, use the upper letters (Z,Y,X, etc.) to avoid this conflict.
Windows allows us to treat shared folders on other computers, or even folders on our own computer (whether shared or not), as if they were distinct drives. This process is termed "mapping the drive" — as in connecting the folder C:\My Documents\MusicFiles on another computer to a drive letter like Z:.
The reason that I’m mentioning the possibility of doing it on your own computer is that (1) I’ve done that in the past and (2) it can cause you exactly the same problem the same way as Ed describes.