How long have you had your glasses? Where did you get them? What is their policy in regards to broken glasses? Do you have vision insurance?
Did the screw come out? If so, that's a pretty easy fix. Several stores sell the little tube that has a tiny screwdriver and screws in it - I've seen them at Target in their Optical center; Walmart also carries them, Lenscrafters, etc.
If it's not the screw, you should take them to where you bought them and see if they can be repaired.