Most frustrating, indeed. But you can and will get over this.
I do know what you mean. If the girl says LJBF/actually rejects you, then there's something to look to, you have your answer, and you can move on. When a girl just "disappears" for no reason, then it could be a little tougher to tell when things are really "over." I feel if a girl is playing these sorts of games, just ignore her for the time being as well, if she wants to re-establish contact, she'll need to do the work. For now, I say move on to bigger and better things, and let her re-establish the contact, don't keep pressing her.