You know that you get old when you can't consider doing something love related via electronic means.
But that isn't relevant here.

If she's on your mind quite a lot (for whatever reason), then by all means contact her. Say you saw her, apologize for not talking to her then and then ask her how she's been.
You may have gained a friend, a romantic interest, ... In the worst case she'll think you are weird but. Anyway it goes you'll at least have gotten this unanswered whatever out of your system.

Don't think it over, just do it. You'll stay unhappy if you wait for thing to get better. Take it from the guy whose first romantic experience started whe she said "are we going to kiss or what".