Is she home yet?? hope she's ok...
im not a parent and im only 22, but i hope i can help...
im with most members here, dont yell at her or anything, if she wants to talk listen...
if she doesnt talk, and she's drunk, wait till she's up, and THEN talk to her, give her a big brother talk, ask her what's going on, and focus on the point that ur her brother not father, so she can tell u anything she wants to...
also, ask her if she wants to end up bieng a big loser and get into troubles, and maybe JAIL
give her examples of people started just like her and ended up wasting thier whole life...
if she's not home yet u might wanna consider calling the police, somthing bad might happened...
good luck...