What song should song for an audition?? i Have an alto voice?

Well since you are auditioning for a play you really should sing one of those "typical musical stuff", but look at the more modern rock themed plays. Check out Rock of Ages..perhaps "Harden my Heart", Spring Awakening.."The Dark I Know Well" or "Mama Who Bore Me"...a beautiful song, maybe something from Glee? Actually the best thing I can think of for you, is "21 Guns" from American Idiot...I just don't know if you will be able to find the music...but you could just get a karaoke track from the original Green Day song I suppose? Hope this helps :)