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How to reset your admin password
To get started, boot the server to a Windows CD. Browse to the repair section and open up the command line tool.
Inside the command line, change directories to the windows installation directory. It will usually be the C, D, or E drive. In this example the D drive contains the Windows system files. Type the following commands:
Ren utilman.exe utilman.exe.old
Copy cmd.exe utilman.exe
This will change directories to the system32 directory and rename the Utilman.exe file, which is the executable file that allows users to open up the Ease of Access menu. This menu allows users to modify the contrast of the screen and access features such as the Magnifier and Narrator. After renaming the utilman.exe file, cmd.exe is copied and renamed as “utilman.exe”. Now when users click on the ease of access tool at the windows login, the command prompt will appear instead of the normal menu.
Reboot the host and start up normally. At the login screen click on the ease of access button in the lower left corner. A command prompt running as the system account will appear.
Now you can either enable and reset the local administrator password or create an additional account and add it to the local administrators group.
Change the Local Administrator Password
Type the following commands to change the local administrator password and enable the account if it’s disabled:
Net user administrator newpassword
Net user Administrator /active:yes
Create an Additional Local Administrator Account
Type the following commands add another local administrator account
Net user newadmin P@ssw0rd /add
Net localgroup administrators newadmin /add
You can now login to the server with the new local administrator password or with an additional admin account. Once logged in, make sure to revert the Ease of Access menu back to normal by typing the following commands:
Copy utilman.exe.old utilman.exe
What if I Am Using Windows Server Core?
Windows server core is an installation option that is available during the initial install of Windows Server 2008 and higher. Essentially this will install windows without the graphical user interface. Read “Benefits of a Windows Server 2012 R2 Core Installation” by Andy Syrewicze for more information on why Server Core should be used. The Utilman.exe file is not included in the install of server core. So when you boot to the windows CD you can skip the part where you back up the utilman.exe executable. Type in the following commands:
Copy cmd.exe utilman.exe
This will copy the command line executable and rename it as the utilman.exe file. When the host is rebooted, it will think the utilman.exe file exists and the Ease of Access button will respond by opening the command prompt when clicked on.