- You may try unplugging the network cable from the domain controller and then reboot DC. And check if you able logon! If so, please uninstall newly installed update.
- Please reboot the problematic server to Safe Mode and try to logon as LOCAL administrator to see whether it works. If so, please uninstall the newly installed update and then reboot the server to test again.
- Repair the Server
NOTES: Please take an in-place upgrade is the final alternative before u have to re-install the operating system. It takes the same amount of time to do the upgrade as to re-install the operating system. Also, some of the customized Windows settings may be lost through this process. Before doing that, you need transfer or seize PDC role to another domain controller.
Link here for In Place Upgrade and to fixup technical problem. Here is Microsoft’s support.
“how do i get a password for a new domain“, sorry I can not provide the answer here, coz it is called one kind of hacking ! I don’t know if you are an administrator or not!
The portion of your question “How do I get to my usual domain?” seems to be the real question. Typically, you can type your domain/Username (mydomain/Myusername) and your original password in at the log-in screen.