If you're attending any form of school, it'll be more than easy. If you're employed you may also be able to find a different group to start hanging out with, assuming you get along with any co-workers enough to consider it. As mentioned above, going to the gym is another possibility.
There's also the chance you could be introduced to a few new social groups by hanging out with any current friends. Most often people have a few different social groups, all you need to do is get out there a little, socialize more, and if you'd like, mention that you're looking to expand your group of friends. It's important to avoid pushing too much, otherwise you may find yourself hanging out with people you don't really get along with simply for the sake of hanging out with someone.