Some party game ideas I like to do with youth group (even now) are:
1. Who am I? - give everybody a name tag with a famous person's name on it, put it on each guests' back. They have to go around the room asking yes/no questions about who they are. ie - am I alive? Dead? male? female? etc.... Since the birthday girl is into music, you can have singers/composers spanning different genres, decades, etc... It depends on the crowd and how easy/hard you want to make the game. Keep a list of who "discovered" their famous person, so you know who to give the prize to (first person to guess who they are wins). It's a good ice breaker game.
2. Scavenger hunt (with a twist) - break people up into teams of 4-5, give each team a list of things to look for. BUT they can only look for these things among their stuff (purses, backpacks, etc...)!! It's amazing what people carry around with them!! The first team to find all the stuff on their list wins the prize.
3. Find the picture - before anyone gets to the party, take a small picture or stamp and place it in the room. Then ask the guests to find "a picture of an eagle" or what ever the picture is in the room. Once somebody finds the picture, they need to QUIETLY go to the side, watching everybody else find the picture WITHOUT "helping". The first person to find the picture gets the prize, but it's fun to watch everybody find the picture, so the game really ends when everybody finds it.
I could go on and on, but these are some of my favorites!! I hope this helps!!