If you should be contacted out of the blue by a friend you fell out of contact with years ago but still remember well and fondly, do yourself the favor of writing or calling back. Do this even if just to say 'Hi' or 'Of course I remember you!' Take a moment to reach out, even if you think you might have grown too far apart or if you're just scared. Don't find excuses. Don't procrastinate. Don't think that it doesn't matter.