Girl trouble

about 5 months ago i was seeing the same girl most mornings at work in passing and was getting smiles off her, never said hi or anything - again this went on for a couple of weeks and suddenly she disappeared - i found out she moved to another department but i didnt see her again. I then tried to reach out on linkedin - i saw her name on her badge. But then she blocked me on linkedin and then i didt see her for like a whole month. I thought forget it leave it. Now im seeing her again, ive ran into her a lot of times in the past couple of months and ive had plenty of opportuntiies to apologise but sometimes she avoids my gaze. Sometimes she looks at me. Ive realised ive never really apologised to her or ask her whats wrong. next time i see her shoud i ask her if i can speak to her and apologise if ive done anything to upset her.
I cant just do nothing because im going to continue to see her and its awkward.