I put the key into the ignition of the car and it won't start...any ideas???

so get a new ignition switch,if its bad it wont come up as a code

hi there.
this youtube video might help you out.
NISSAN MICAR k12 WON START OR TURN OVER RANDOM PROBLEMS WITH IGNITION
or this google link.
Nissan micra k12 won start Google Search

The switch must match the key code.

put the working key into drivers door and unlock it, then the good key should start ignition

Make sure your steering wheel isn't locked. Sometimes a key won't turn until you jiggle the wheel while trying to turn the key.

The ignition start circuit is the path from the ignition key in cranking mode to the solenoid on the starter. The path travels through a starter relay and a neutral safety switch before it reaches the starter.
This must be the circuit not working on your car.Make sure battery and starter connections are tight.Check for power at the starter solenoid terminal with a testlight when someone turns key to crank. If you have power there, they sold you a defective starter. If you have no power there then it could be the relay or the neutral safety switch.

This happened to to me with my ranger. I went and bought in ignition and a junk yard and no problems after that. That way your not out of a lot of money.

hi,it maybe a good idea to remove the steering collum covers to visually inspect it can be the ignition bolt just being loose or the steering lock or ignition it self is on its way out.

how warn down are the keys? from wear and tear the do eventually wear down till they dont work try that, or if it is cold out side then try putting it in some heat it could be froze if that dont work.... BUY A DODGE!!! lol