Hate her. Hate her in every way you can. Think of every shitty thing you can, about her, and get good and angry. Pissed off. Hate her guts.
Then, when you realize you still really like her and can't hate her, the feelings will all rush back. Write about it, talk about it, jot down cheesy emo poems on paper and then crumple or tear them up in anger.
Go do some things that make you happy, some guilty pleasures, comfort foods, video games, however you unwind. Whatever you do, don't give in to any temptations to call her, text her, IM her,
fox her, or send a carrier pigeon to get in touch.