Technique 1 :: Local Users and Groups
The first way to enable the built-in administrator account is to open
Local Users and Groups. You can do this by right-clicking on Computer and choosing Manage.On the Computer Management screen, go ahead and expand Local Users and Groups and then click on Users. You’ll see the Administrator account in the right-hand pane.
Right-click on the Administrator account and click on Properties.
Go ahead and uncheck the Account is disabled box. Now you can log off or switch user your current account and you’ll see the Administrator account show up in the list of users.
Technique 2 :: How to enable Administrator account from Command Prompt
you have to go to the start screen and then right-click and choose All apps.
find out Command Prompt under Windows System. Instead of clicking on it, you need to right-click on it. This will bring up options in a separate pane at the bottom of the screen.
You’ll find out options below, You need to click on Run as administrator and then it will open the command prompt with Administrator permissions. may be one permission box will appear so just click on YES. now type following command to enable the built-in Administrator account:
net user administrator /active:yes
Its done Enjoy !!!!! :)