How do you get over a girl that you met and really liked but will never see her again?

This is my situation, I met a really pretty girl at universal studiOS and I really liked her. I never got a chance to give her my number because i didn't have any paper on me at the time. To be completely honest, I never talked to her. I just smiled at her and she smiled back. Then she would just glance at me from time to time. So we had a lot of eye to eye contact, she had dark blue eyes. What would I do?

I'm 13 btw