why will my van not crank? on 2002 Dodge Ram Van 1500

i have put a fuel pump, a water pump, a crank shaft sensor, checked all the fuses, made sure it has gas , put a new distribtor on it ....don't no what else to do please help with info asap....thanks

Asked by for the 2002 Dodge Ram Van 1500
If you mean it cranks but no start it can be the computer. mounts on firewall
above engine with three bolts and has three plugs.Cost $289 exchange
with lifetime warranty.Do you have any other symptoms ?