If she doesn't remember you maybe you weren't that attractive or interesting to her :O
Don't know, it could be a reason...
On the other hand, she might have bad memory and it might take some further texting to make her remember you
But I wouldn't ask her out for coffee or anything just yet. If she doesn't know who you are, why would she go out with you?
Make her remember, be specific if you want; if she doesn't then I'd say forget about her.
FB might make her remember after she sees your face. But, honestly, if she can't remember you at all, maybe you didn't play it that smooth the night you met her.
Any ways, give FB and texting a chance and if she does remember you, then ask her out
