You're screwed.
Mistake 1: You didn't get the right number in the first place
Mistake 2: You asked the friend for the others number. Allow me to assure you, when you asked the girl who likes you for the other girls number this is how it went in her head: "He likes her and not me!? How dare him! I'm not helping him get with her! In fact i'll ruin any chance he had with her!" and then she called up her friend, and told her that you asked for her number because you were too shy to ask her or some **** and they'll laugh about it.
Yeah, maybe i'm wrong, but it's pretty damn likely. Remember, girls are self centered attention mongers and they would rather bite the bullet than put another girl in the spot light. It's just the way it is.
Mistake 3: You haven't moved on yet. This is an error because you are allowing yourself to be at their mercy. You hang in limbo, going crazy, waiting for some kind of answer, yet she probably isn't even thinking about it or you. Sad truth, but accept it and move on.
The only alternative to try is to try and hangout with the two of them again as someone suggested and get her number from her directly. Much more smooth. You could pull this one out of the crapper by doing so. Otherwise, move on.