My car started fine a couple of days ago and today when I went to start it, it won't even turn over. The lights work, the battery is only a year old. Not sure where to check next.
You indicated above that there is 'soft clicking' when you try and start the car. My bet is a weak battery - you can still have headlamp power, but not enough charge in the battery to turn over the engine.
Try this, turn on the headlamps and have someone stand in front and observe the lights as you turn the key to start - if the headlamps dim way down, it's most likely a weak charge of the battery.
You can also just go ahead and try and jump it - it won't hurt anything if your battery is charged.
Also check your fuses - there will be a large fuse (~20 amps or more) for the starter.
I don't think the it will be a flat battery, since a flat battery will usually caused a repeated clicking of the starter solenoid and a flickering of the dash lights when you turn the key.
Either the contacts on the relay you can hear clicking are faulty, so there is no power getting to the starter solenoid, or the control wire on the starter solenoid has disconnected, or possibly the starter solenoid is faulty.
If you can identify the starter relay in the fuse box, you could try swapping it for an identical one.
Check also that the thin wire is securely connected to the starter solenoid on the side of the starter motor.
You could try connecting a wire directly from the battery positive terminal to the small control connector on the solenoid to see if it then operates. Make sure the car can't move if you do this.