I am having similar issues to OP. I have a Toshiba Qosmio x875 with Windows 8.1 (computer came with Windows 7, I upgraded immediately to Windows 8, and updated to Windows 8.1 in October when it was released).
Tonight, I was watching a DVD using Windows Media Center. When it ended, I clicked the stop button and ejected the disc. Then, Then Windows Media Center screen froze for 5-10 minutes. Eventually, I received an error message from a screen I had never seen before (I figured that the update to Windows 8.1 changed the way errors looked and since I don't remember anything like this since updating to Windows 8.1, I didn't think much about it.). I don't remember the error message, but I think it said that there was a problem and that it was reporting the error and that if I wanted to look it up...I didn't write down the information. Upon reboot, I got a black screen that said "No bootable device"...After waiting for 30 minutes, I finally pressed the power button and turned off the computer. When I turned it back on, I received the same message.
I pressed the power button again, unplugged the laptop, removed the battery, and pressed the power button for 30 seconds. Then I replaced the battery and power cord and turned it back on. Now, I decided to put in my recovery discs. I think I was offered 2 options: 1. a Toshiba recovery (which when selected said it would take me back to factory settings and wipe out all of my data) and 2. I think this was a generic recovery option. This time I selected the second option and tried to refresh my pc, which gave me the error that brought me here: The drive where Windows is installed is locked.
I was able to access the BIOS (or is it UEFI now?) and both internal drives show up there. I called Toshiba and they just want to wipe out everything and reinstall Windows (and charge me $160), which I have the knowledge and ability to do myself. The problem is that I recently suspected a problem with my external drive, so I transferred the files to my desktop until I could buy another external drive.
So, that brings me back to this thread. So far, I have done the following:
diskpart
list disk (shows disk 0 online, size 931GB, free 931GB and disk 1 online size 931GB, free 0B...this worries me because I assume that 0 is my OS, so it shouldn't be empty and disk 1 shouldn't be quite that full)
select disk 0
select partition 1
Then, I get the error:
Virtual Disk Service error:
The disk is not initialized.
I hope that I have given you enough information. If not, I apologize...just let me know what else you need.
I'm not sure what caused this. I have been using 8.1 since October without any problems and have seen no indication that my hard drive is failing up until today. I suspect (hope) that the hard drive is fine, since it is still recognized. I would be happy to do a clean install of the OS once I recover my important (irreplaceable) files.