No Windows Build Support

I was going to build my game as a windows standalone, only to say ‘no modules installed’; I could only build a web player. I look for a solution online to re install the download manager from the unit website and only check the module I want in the setup. However, there is no windows build support, there is Mac, Android, Linux, etc.
Please help as soon as possible.
Thanks in advance.

EASY!

REINSTALL UNITY

Just ran into this myself. There is no checkbox.

The solution, indeed, is to reinstall unity, as administrator.
I just ran the install.bat as admin and it works OK.