Windows won't boot. Black screen with blinking cursor at the corner

I have seen this happening a few times, mostly on Hyper-V guest machines.

The solution is simple.

Boot using the CD or ISO and go to the recovery options. Then open the command prompt.

Type bcdedit and press enter

You should see the windows boot manager in one partition and the loader in another one. If that's the case, then type:

bootrec /fixmbr and press enter
bootrec /fixboot and press enter
reboot computer

If that was not the case, try typing:

bcdboot C:\Windows

But make sure the Windows directory is in the C drive, if it is not, replace with the correct letter.