If you are on Windows 7, and did not disable System Restore, you may be able to recover the VM from the Shadow Copy.
Just open the Properties of the folder it was in, and click on Previous Versions.
With any luck, one of the versions will be old enough to still have the VM, but new enough that it's actually useful. (Usually, most of the restore points are created when installing Windows updates. Restore points are cleaned up automatically.)
If you find a suitable restore point, do not use the "Restore..." button - that will overwrite everything else in the folder, too.
Use "Open" and copy the subfolder containing the VM.