How to regain a diminished social life?.

I’m in the fourth quarter of my Junior year, and after having spent the majority of the year studying and trying to do well in school, I’ve come to realize that my neglected social life has all but vanished. The last time I actually went out and had fun with a friend was about a month and half ago, I have been to a total of two parties in the last year,and I rarely hang out with the people I enjoy speaking with at school. I’m in a sort of a flux as to what I should do in order to pick up the pieces, and I’m even starting to worry that I’ve forgotten how to have fun with friends. What would you do in this situation?