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
* 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.