Unable to crank the van on 1996 Dodge Ram Van 2500

Our van shut down on us while going down the interstate at 70 mph, when we tried to recrank it, it would not. My husband and I took the front of the engine off thinking it was the timing chain broke or the distributor but neither one was the problem...what could be the possible problem?

Asked by for the 1996 Dodge Ram Van 2500
Does the engine crank over? Can you turn it over with the starter or by hand?