If your 1996 ford windstar cranks but won't start what could be the problem?

I hear that the problem is the pressure to the fuel pump. Also have heard that the alternator is the problem. To be honest, I cannot figure out why mine will not start either. I have replaced the fuel filter, O2 sensors, thermostat, reset the inertia switch, and spark plugs and wires.... nothing has worked yet.

I have had the same problem, 2cd Explorer. I replaced the fuel relay. No problems now