The Recovery Console Administrator password on a Domain Controller is the same password that you used when you promoted the server to a Domain Controller.
This password is local to the server and is different from the Administrator password that is stored in the Active Directory.
This password is stored in the local SAM (Security Accounts Manager) registry hive at %SystemRoot%\System32\Config and each Domain Controller has its' own non-shared, non-replicated copy.
To change the Recovery Console and Directory Services Restore mode password:
1. Shutdown and Restart in Directory Service Restore Mode (Press F8 to view advanced startup options).
3. Open a CMD.EXE prompt and type:
net user administrator *
NOTE: You could also Start / Run / Lusrmgr.msc / OK.
4. Shutdown and restart.
You can now use the Administrator account to log on to the Recovery Console and to Directory Services Restore Mode, using the new password.
If you forgot the password for logging on to Directory Service Restore Mode, see tip 1984.
You could also demote the domain controller to a standalone server, and re-promote the server using Dcpromo.exe. You will be required to enter a new Directory Service Restore Mode Administrator password.