Disco, the best advice I got about break-ups was this (from a wise woman): if your girlfriend breaks up with you, all you can do is accept it. If you try to get her back, she will think that if she takes you back now nothing has changed. She will have shown that she will give in, and so you will not have a need to change.
So the only thing you can do is accept the break-up. Only then will the girl start thinking that okay, we have truly broken up now: now, is there a way we can get back together and start from scratch? Also, only then will she start feeling the emptiness of being without you.
But perhaps it was you who broke up with her. Or both of you agreed. Regardless, the same applies: acceptance is the only way to go. Only then can you both approach each other again, after a clean break with the past.
But it is harsh of her to delete you from everything. Change her number? Come on, who does that! Never heard of it. And it is customary to at least send an email or something, a week or so after the break-up. See how the other person is doing. Even if you have broken up, you are still two adults who have spent a lot of time together for a long time, and basic decency says you should at least find out if the other person is doing okay.