Freestyle line is not showing Im following this tutorial on YT https://www.youtube.com/watch?v=ZiqrCRqyLzE. But freestyle line does not appears. Freestyle checkbox is ticked, add-ons are ticked (LoopTools, PieMenu Official). I tried it with new fresh blender project, but nothing. Im in Blender 1.78, Win 7 Ultimate x64.





Just editing and adding my file since I am doing the same tutorial and having the same problem: 

Adding a camera to the scene worked! (I am adding this here since I cannot comment yet) Thanks a lot!
Regarding the file attached try adding camera object to the scene, for some reason Freestyle lines render only if it's present. 

It's probably a limitation however you won't be able to output an image without a camera regardless unless taking a screenshot of the preview render (although in Cycles Freestyle lines will be rendered only in the final aka F12 render so screenshot won't work as well).