Eyeglasses are very fragile and relatively expensive to fix or replace if they break. While some fixes may be temporary, there are several ways you can fix your eyeglasses, either until you can see a professional or for permanent use.
Use thin wire and pliers if you don't have a screwdriver and a screw. Insert the wire in the hole where the screw should be located. Wrap the wire around the inside of the frame a few times before twisting the ends with the pliers so they don't scratch you or the glasses. Again, work with the arms of your eyeglasses open.