Will not start

My son's car was running before the battery died and was sitting in the driveway until he finally bought a new one. Now the car won't start or even crank and the radio won't come on either, everything else comes on. The dashboard lights, headlights, electric seats work, etc. I checked the starter fuse under dash and it's good. Is there a starter relay or is it a factory kill switch I don't know about?