Re: so....
If you have one DC then you absolutely MUST have a second. Or more, depending upon your environment. Never perform maintenance (eg patch) on them both at the same time.
So, a single loss of a DC isn't a big deal. As suggested above. Nuke it. Metadata cleanup. Re-install - FFS give it a new name, even if you must keep the IP address.
When replicaiton is finished THEN you reboot the other one.
This is "basic stuff 101".
PS: You can back up a Domain Controller, but you can never restore it. Write a 500 word paper on why not by Monday morning for 10% of your grade.
PPS: What do you mean you installed Exchange on the DC / File server on the DC / ERP on the DC? You don't.
"There’s no point in acting all surprised about it. All the best practices and planning charts and have been on display in your local planning department in Alpha Centauri for thirty of your Earth years, so you’ve had plenty of time to lodge any formal change request and it’s far too late to start making a fuss about it now.
What do you mean you've never read the documentation and best practices? Apathetic bloody administrator, i've no sympathy at all"