Windows Defender can be found in Control Panel if you change its view to Small/Large Icons (the default view is Category).
You can also create a shortcut for Windows Defender on your desktop for quick access.
Just right-click anywhere on your desktop and navigate to New > Shortcut.
Enter the following code into the location area (without the quotes):
Then press Next, type “Windows Defender” as the name and click Finish.
Have in mind that Windows Defender is disabled by default if you have Microsoft Security Essentials installed.