While conducting some remedial work on a previously closed question regarding the non-resolution of the Time Machine Backup problem, another situation arose involving the disappearance of the Windows 7 Virtual Machine from the Parallels 7 Desktop.app.
On 24 Dec 2013, in the Application Launcher window, the Windows 7 Application folder disappeared! In selecting the Parallels Desktop.app icon on the Mac OS Desktop, an error message was displayed:
“The Virtual Machine is not available
The virtual machine files have been moved or deleted. If the files are on an external device, reconnect the device. You can also remove the virtual machine from the list, or manually locate its files.
Cancel Remove Locate”.
The Windows 7 icon disappeared from the Desktop. It was replaced by a large “?” on the display.
Regrettably, I accidently hit the “Remove” option!
In an obvious panic-mode reaction, I conducted a reinstallation of my Windows 7 Home Premium, from the original x64 DVD. Regrettably, I did not exercise sufficient good sense to use the System Restore option on the Installation process (although I do not recall it being displayed as an option!)! I also do not recall seeing the usual warning that continuing with the reinstallation process would delete all data from the relevant storage device (V:\ on my MacBook Pro, OS 10.7.5). Hence, all my applications and associated data were deleted from the Mac OS system!
There were 135 Windows updates (473.5 MB total) required for downloading and installation. After more than 35 minutes of downloading, a “low memory warning” was displayed. The installation process stopped after 127 completions. The remaining 8 were downloaded and installed separately.
Following the reinstallation and updating of Windows 7, the Mac OS had to be rebooted, and the Parallels Tools reinstalled (took over 35 minutes). There were also several further Windows Updates required.
Note that the last Mac OS backup (to the USB 3.0 My Passport 1 TB) external HD was completed early in the morning prior to the catastrophic loss of Windows 7 – Parallels Desktop.
I also note that, in investigating whether a recover/restore operation from Windows Backup application would resolve the problem, I could not get to select the USB External HD (My Passport Essentials-320 GB) as the backup device, despite it having been previously used successfully (last one on 16 Dec 2013) for the Windows Backup process.
Following advice provided by einosullivan as part of the closed question
"Sorry to hear your Parallels VM disappeared. If you've backed it up to an external HD, you can simply copy it back into the Parallels folder on the HD of your Mac (you might want to rename it as there could be a new VM in that folder too).
The Parallels VM file has the extension .pvm
The Parallels VM folder is located in /Users/bruce/Documents/Parallels
You simply launch Parallels and then select the OPEN command from the File menu or the Parallels Virtual Machines window and browse to the .pvm file you copied back to the HD."
the renaming of the two Windows pvm files, the Parallels Desktop.app reverted to the display of a “?” in the window, plus an error message:
“The Virtual Machine is corrupted
The virtual machine cannot be used because its files are corrupted.
I have taken no further action pending the Experts-Exchange response to this new question.