Come risolvere Total identified Windows installations 0

Allora, ieri il server (Windows Server 2012 R2) non si avviava più.

Ho seguito diverse guide, ma alla fine ottenevo sempre lo stesso errore:

C:> bootrec /rebuildbcd

The bootrec command will search for Windows installations not included in the 
Boot Configuration Data and then ask you if you'd like to add one or more to it.
Scanning all disks for Windows installations.
Please wait, since this may take a while...
Successfully scanned Windows installations.
Total identified Windows installations: 0
The operation completed successfully.