My Caravan periodically shows no digital display on the odometer/tripodometer when I turn on the ignition. Gauges do not function and the overhead display goes blank. I know from experience that means the car wont start. It will crank and try to start but fails.
A bad electrical connection thats effecting the ECM, and or the BCM. Sorry to be so vague, but unless you have a understanding about electrical trouble shooting its best to take it to a professional that specializes in electrical.
All of those things get power (12 volts) through the ignition switch (not the ignition LOCK).
Click on this link for a drawing of the ignition switch: http://www.autozone.com/servlet/UiBroker?ForwardPage=az/cds/en_us/0900823d/80/1a/49/a2/0900823d801a49a2.jsp