Bruce,
There is no way to tell what your problem is without more information, but the most common cause for the condition that you described is the ignition solenoid that is located in your left front electrical bay. When you turn on the ignition switch, it turns on this solenoid, and it powers virtually every thing that is controlled by the ignition switch.
If your engine shutdown was caused by this solenoid, you would have lost power to other things that are powered by the ignition switch, and a drop in the dash gauges would have been noticeable if you were watching. Sometimes the loss in power is momentary, but long enough to kill the engine, and sometimes it will not come back until you cycle the ignition switch.
If you replace your ignition solenoid, only use a continuous duty solenoid with at least an 85 amp rating. These solenoids fail so often that I always carry a spare.
Gerald