Depends if the OP is up to working at the moment though. There's this social inclusion thing round here, maybe there's a similar scheme near you... if you don't want to try new things and go out to new clubs etc on your own, or anything really, you can get assigned a volunteer who will go with you to up to 6 things, it makes the first time(s) less scary (apparently, though I'd have thought meeting the volunteer was quite scary in itself at first). That's if you feel you need someone to do it with you of course, if you want to go ahead and go to a class of some kind or join a club, that's a great starting point.
Oh and about Facebook - BAD idea. You will find all the people you used to know and they will undoubtedly have loads of photos of them having a fantastic time wherever they are now. It won't make you feel better, lol!