What would cause my van to die and not start back up?

Too many possibilities, from fuel , to ignition,vacuum problems , position sensors , ignition switch
However you can help to get an answer by having the fault codes read first then commenting on the codes to help with your problems
Always include all details of the vehicle ( make ,model year ,engine type ) in your question

I don't know if ur van is diesel or petrol engine,but I wil giv u clues for the both so that you can trouble shoot.
If its petrol engine check the fuel pump,fuel filter, plugs,coil, distributor...
If its diesel test the feul pressure by doing the pressur test!!!