There seems to be lot of bad managers here justifying your boss's behavior. Don't buy that. Seems like you have a bad manager who seriously lacks communication skills and doesn't care about your growth if he has been ignoring you for months. It could also be that his priorities are different now where you don't fit it, still that doesn't excuse for poor communications. This is the reason why regular 1-1 meetings are so important. Does he do that or no?