Me temo que vas a tener que reiniciar la contraseña del administrador de dominio:
	
		Here is the steps to reset Windows server 2008(R2) local and domain password
	
		Method 1: reset the local and domain administrator password on Windows Server 2008 with just the Windows Installation Disk
	
		* Insert the original Windows Server 2008 installation DVD
		* Reset the computer, boot from DVD
		* Choose option "Repair your computer"
		* Start command prompt
		* C:\
		* CD C:\Windows\System32
		* MOVE Utilman.exe Utilman.exe.bak
		* COPY Cmd.exe Utilman.exe
		* You may also need to "Enable" the administrator account which can be done by using "NET USER administrator /active:yes"
		* Restart windows
		* At the login screen, type Windows-U, this fires up cmd.exe now
		* NET USER administrator Presto! Login as administrator!
		* Now repair computer again and move the original Utilman.exe back
	
		Method 2: Third party password recovery toolkits
	
		Step1. Download "Windows Password Rescuer Advanced", and install in any available computer.
	
		Step2. Create a bootable CD/DVD or USB flash drive. (A blank CD/DVD/USB Flash Drive is needed)
	
		Step3. BIOS set. Boot computer from the created CD/DVD/USB Flash Drive and set BIOS setup.
	
		Step4. Reset Windows Server 2008 or 2008 R2 password instantly.
	
		If you want to read more information:
	
		How to Reset Windows Server 2008 Local and Domain Password.
	
		 
	
		 
	
		Saludos,