The engine not turning over is related to your starter circuit or your starter relay. If you have a good battery and your relay is functioning, you will here a clicking sound as you turn the ignition key to try and start the car.
The power windows and radio have their own circuits, typically dedicated to the use. Radio, circuit, window circuit, lights, etc..
If your battery is in good shape, you may have a main fuse issue for the overall vehicle. Checking fuses with a multi-meter to ensure they are in working order rather than visual inspection is recommended. I've seen fuses that appeared fine but were not when tested for continuity.
Starting at the batter to ensure it's in good working order is recommended. All of these symptoms can be attributed to a bad battery.