I'm having this kind of black screen since I installed dotnetFX40 from Microsoft webpage. It needed to be restarted and that is what I actually did and got a "welcome" message:
Windows failed to start. A recent hardware of software change might be the cause. To fix the problem:
1.Insert your Windows installation disc and restart the computer.
2.Choose your language settings, and then click "Next".
3.Click "Repair your computer."
If you do not have this disc, contact your system administrator or computer manufacturer for assistance.
Info: The boot selection failed because a required device is inaccessible.
The problem is that I've already tried "Repair your computer" and even via command prompt using Bootrec /rebuildbcd. In the end, I used System Restore to earlier point and even that gave me no way to get Windows back. The biggest problem is that I have to finish my presentation and I am not gonna reinstall Windows!
EDIT: I can't load Safe Mode menu either.