Heya! Well, kudos to you for realising that you need a change, because if you hadn't said that, then I'd be typing out a reply now telling you that.
What happened to your friends from high school? How long ago did you finish? Unless you're an entirely repulsive individual (which I seriously doubt!), people won't turn down social engagements just for the sake of it. Ring 'em up, even if they're people you don't know too well, and suggest something - pizza, bowling...whatever.
You said you want a radical change...if you could achieve anything at all, what would it be? Now's the time to start working towards it. Set yourself a goal and take steps to achieve it: you'll only make things better for yourself.
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One drop is lonely
Two drops okay
Three drops can make a spray
Four drops get carried away