I’ve been using dvdab virtual drive software to emulate a dvd drive, it had been coming up as drive T:. A few days ago it came up as drive S:, the same as my WD. Win 8.1 DISKMANGER now showed the WD, as uninitialized. I uninstalled dvdfab, rebooted, but the system would not allow me to assign a drive letter to my WD. I did a quick format; now it is back to S:. Fortunately I did not have too much of importance on the WD. How can software cause a HD to become dormant?