Reconnecting with people -- how does it work?!

As I mentioned the other day when I complained about where I live, I desperately miss my friends, and I feel terribly isolated from them. There's a certain few I haven't talked to in FOREVER that I'd really like to get back in touch with, but I keep feeling discouraged. I have major social anxiety issues even with people I like, so I keep worrying that if I send them a friendly Facebook message or whatever, they'll think I'm super weird and not respond. And to be clear, these aren't people I've had a falling out with or anything — they moved, I moved, life got hectic, etc. and we lost touch. Does anyone have positive stories about reconnecting with old friends? I've been really missing my friends to the point of feeling depressed, and I think reaching out would help me deal with that.