van will not turn over

Which area of the vehicle was damaged? Sounds like some kind of issue in the starting system itself, causing high resistance to the starter. A wire could be loose or dislodged (battery cables, etc...) The starter relay could have failed. Certainly concentrate your investigation at the location of the collision, as there is probably a "smoking gun" to be seen somewhere.

try boosting it,if that doesnt work check for power going to starter