I was very sad when I was not able to make it work… You know something happened to my Hyper-V server and needed to reinstall it. I made a clean installation and after it was set up I tried to import / run existing virtual machine back in… But then I read the articles about import and export of virtual machines… And I already saw myself reinstalling my virtual machine again. But NO! You can put it back to life folowing this steps:

Let’s assume that:

I have a VM folder located on D: so D:\VM and in it my virtual machine called machine01 with vhd called machine01.vhd (I had also a snapshot but it was lost during this procedure becouse I did not copied it… So I did not tested if it also restore snapshots… I only wanted my machine back to work…).

When you establish Hyper-V system again rename your current machine folder to let say machine01old – after that create a new virtual machine with the same hardware configuration as it was the machine before (and also with same location so d:\vm\machine01). When machine is created use Export to export it (not only configuration files but everything). It will create let say d:\Export and in this folder there will be three other folders.  Move or copy your original VHD to the location in Export\Virtual harddisk and you are ready… Your machine will start without problems.

 As I said this test was made a hour ago and I lost my snapshots but I did not care to restore them I just wanted my virtual machine to get back to life…

So as a conclusion… Hyper-V can be restored even if you are a bad administrator :) like I was in this case.