2004 chevy impala will not start

Are you saying the starter motor won't even crank the engine? No electricals work, anywhere? Make sure battery has a full charge and battery connections all good. I haven't looked to see if fusible links are involved? Use a test light at you fuse box, check for voltage at the fuses. Some fuses are hot all the time, some go hot with the key on, check them both ways. If your only missing ignition feed, I'd have to check feed to and from the ignition switch.