How can i start my renault megane dsi?

the car all of a sudden is not reading my card when i try to start it up , i got in the car to start it, one ov the kids ad put it in gear, i didnt realise it jerked then nothing, i av tryed to start it, come out ov the car, put the alarms on went back into it and still nothing . its if its not reading my card

Amanda
April 2011