Hi
Most likely the easiest is - if you have a working config-backup - is as follows:
- Check you have backups working - they include a config backup.
- Delete your AD!
- Restore the last good config backup from before the problem. This will reinstall the AD, if needed also the network.
This has helped me / my clients several times… 
And it has helped others too:
Good luck also helps!
My 2 cents
Andy