I dated a girl for about 3 months until she dumped me for reasons she won't tell. I haven't spoken to her at school at all we just ignore each other. I really want to ask her out again, but I can't get her attention or pluck up the courage to ask her. What should I do?

I dated a girl for about 3 months until she dumped me for reasons she wont tell. I havent spoken to her at school at all we just ignore each other. I really want to ask her out again, but i can't get her attention or pluck up the courage to ask her. What should i do?
Leave her alone, or you are subject to be labeled a stalker.

I know that she likes me and I like her but I haven't asked her out yet