Reset the Windows Server 2012 Administrator Password
Before starting a quick tip:
You should never work with the “Administrator” account, each admin has their own account as it makes troubleshooting easier if something is messed up and another reason is if one admin forgets his password, another admin can reset it.
Now I will guide you step by step how to reset password, if you have forgotten the admin password for your Windows 2012 server. This guide also works for Windows Server 2012 and Windows Server 2008 R2.
Step 1: Boot from a Windows Server 2012 R2 DVD
Step 2: Click Next when Windows Setup loads.
Step 3: Press SHIFT + F10 to open a command prompt.
Step 4: At the command prompt (to make backup for utilman.exe), enter:
move d:\windows\system32\utilman.exe d:\windows\system32\utilman.exe.bak
Note: you may need to change drive letter d: with c: for Windows Server 2008. If you are not sure about the drive letter, please search for drive that contains the windows server.
Step 5: Replace utilman.exe with cmd.exe:
copy d:\windows\system32\cmd.exe d:\windows\system32\utilman.exe
Step 6: Remove the boot media from the server and tell Windows PE to reboot:
Step 7: Once your domain controller is running again, click the Utility Manager icon or Press Windows Key + U
Step 8: At the command prompt, reset the domain admin password with this command:
net user administrator your_new_password
Step 9: Close the command prompt and log on with the new password.
Step 10: For Security reasons, it is highly recommended that you restore the original utilman.exe. For this, you have to again boot Windows Server setup, follow steps 1-3, and then enter:
move /y d:\windows\system32\utilman.exe.bak d:\windows\system32\utilman.exe
Step 11: After you removed the boot media, you can reboot the server again with:
Your Server is back up and running once again now.