I have a Dell XPS 8100 with Windows 7. I found I had to take a bunch more steps. Many probably not necessary but as I proceeded with each step, I didn't revert any of the changes from the previous steps.
I found when I originally ran the commands posted above, I was getting errors. First, using the command line while logged into Windows installed on the C drive lead me to some permission errors. I changed all my permissions on the D drive where the recovery files were to allow for every user to make all changes. I figured I had to eliminate any possibility.
Then imagex would start running but would close out. I decided to try the command prompt that is part of the windows 7 install dvd that came with the computer.
I booted off of the DVD by hitting F12 at the Dell startup screen. Then selected DVD when the menu came up. When asked to hit "any key" I hit the enter key.
The computer booted off of the DVD. I selected Language, then clicked Next.The Windows 7 Install Screen came up. I clicked on "Repair your computer." When the System Recover Options window came up, I clicked on "Use Recover Tools...." with the Windows 7 installation automatically selected. I clicked on "Next." Then it asked me to Select a Recovery Tool. I selected "Command Prompt."
Here's where I got stumped for a while. I couldn't figure out how to get to the directory I wanted using the command prompt since I'm so Windows oriented. I assumed that the flash drive letter would be the same after I booted from the DVD as when I transferred the WAIK files. I was wrong. I had to find the correct drive letters to be able to go to the right directory.
I sort of stumbled onto my method, as I'm sure more techy guys know how to do this better. Back on the Choose a recovery tool screen, I clicked on "System Image Recovery." That initiated a search of a system recovery image which I knew didn't exist since that was the reason I ended up here. I hit cancel.
The next screen automatically default to "Select System Image" so I clicked "Next."
The next screen was a "Reimage you Computer" screen. I clicked "Advanced."
The next screen gave me an option to search the network for an image, which I couldn't do since the Windows 7 reinstall didn't come with network drivers. I clicked on "Install a Driver." I clicked "OK." This opened up a window with a "Computer" icon that when double clicked allowed me to see all the drive letters for the drives I needed. My Sandisk Cruzer drive letter had changed from K to L.
So then I Canceled out of three windows to get back to the screen with the Command Prompt options.
When opened, the prompt was "X:\Sources"
I had to get to the L drive, but the little experience I have with using the command prompt was keeping me from getting there. Then I found this link which is really for Vista installs:
I followed the suggestion Posted by eddyneo2000 on 13 Feb 2009 6:15 PM but modified it for my L Drive. So I typed, "path L:\windows;L:\windows\system32" and pressed the ENTER key.
Next I typed "L:" and pressed the ENTER key
Next I typed "cd amd64" and pressed the key. I tried the imagex executable in the x86 directory but it didn't work. Since my original install was a 64 bit system of Windows 7 I thought I'd try the imagex file in the amd64 folder a try.
Then I typed "imagex.exe /apply d:\dell\image\factory.wim 1 c:\" and hit the ENTER key.
I was finally in business. The factory image was mounted and was starting to replace the files on the C drive. I could tell because I kept getting a bunch of warning messages that files were "in use." Every now and then, the progress line showing the %age complete wouldn't come up but I let it go until I could definitively tell it was done. I can't remember what the command line said at the end but I could tell it was done.
I typed "exit" and pressed the Enter key. The command screen closed and I exited out of the windows install dvd. I think rebooted using one of the "Reboot" buttons on one of the screens and the computer booted back into the original factory condition.
Just a word of warning though, if you leave the flash drive in while rebooting, the boot sequence will see it (at least on my XPS 8100) and won't move past a couple of screens during the booting process because the computer is trying to boot off of the flash drive. If you forget and the boot hangs, take the flash drive out and press the power button. The computer will shut down. Press the button again and it should boot properly through to the C drive.
Hope some of this information I posted helps. If anything, it will help me later if I get into a similar situation where I have to revert back to the original factory image.