Go to Options tab, select Boot Options, and then Force BIOS Setup:
In the BIOS go to “Boot” tab, Then stand on the “CD-ROM Drive” and hit the “+” in the keyboard to get the CD-ROM to be first, and hit F10 to save and restart
Then in Command Prompt enter the following commands (In most cases the drive should be C and not D like in the example):
Eject the windows media and reboot the server back to the lock screen
From the lock screen you can either click WIN + U in the keyboard or just click the “Ease of access” button in the welcome screen, This will try to open the ease of access executable (Utilman.exe) which is actually right now cmd.exe and will run it with highest privlages:
From that cmd window you can just use: “net user administrator NEWPASSWORD”, but in case the administrator name was changed you can also do what I showed in the screenshot to first find the administrator name:
Don’t forget to reinsert the media, boot into Troubleshooting again and do the following in CMD (Otherwise you will not have “Ease of access” anymore):