Why does Safari OS X no longer open full screen, and why won't the little green circle make my window full screen?

I have been watching Netflix on my computer and made the mistake of quickly cleaning my keyboard (pressing a bunch of random buttons) while a video was playing. Ever since, my full screen option won't work on my Mac on Safari or on Netflix. I know that the little green button is supposed to make it go full screen but it won't do it and a little error sort of noise (like when you click something that is out of your frame) goes off. It does the same thing while I watch Netflix and try to use the little fullscreen button on the video.