Both of the advice given above is a little misguided.
There is no need to next her right away just because she was drunk when you met her. Thats crazy. You just need to see where you're at with her. She might remember you and she might not, but theres no point in just assuming that she doesnt remember you just cuz she was drunk.
So, start with just sending her a message on facebook just to see what type of response you get. That will tell where to go from there. So, you can just send her a message like:
"Hey sillyface/bratface (some nickname) I can't believe you said XYZ (referring back to something she said or did at the concert) I'm gonna have to keep my eyes on you
" OR
"Hey *nickname* It was nice meeting you the other day, you seem fun. Just hope you don't turn out to be a psychoo
"
Something like that. It doesn't really matter, you just wanna see how well she remembers you and how she's gonna respond to you. If you get ANYTHING back thats somewhat significant, just assume that she's still down and she's still into you.
Then after like one or 2 messages back and forth (no need to drag it out), just say something like:
"Look, facebook is a horrible way to keep in contact, send me your number. If we still like each other on the phone, maybe we'll hangout again"
You can even keep it as simple as "Hey, whats your number"
It depends on the type of responses you're getting from her.
Then call her and set up a date.
Simple. Don't overthink it.
CHAT