I have an musical audition soon, and I don't know what to do !!!

It's always 安全, 安全です to pick a classic (e.i. sound of music, 音楽 man, my fair lady). That way if there is someone there to accompany あなた they're sure to know the music.

If あなた have 歌う talent but have problem reaching the high notes i'd suggest something によって Josh Gorban. His songs also sound fantastic a cappella.

If あなた don't have time to learn a new song then just pick a favourite one of the ones あなた can't help 歌う along to when it comes on the radio. if you're having fun it we 表示する in your performance.

Dress nice and comfortably, tie your hair back, and good luck. :D