Not knowing what you have tried and assuming you don't have the security light flashing...
Check your fuse block and verify it's not blown. Verify you have fuel pressure (50 -60 psi) should which remains constant for a period of time after the power has been removed. If you do not have the pressure its probably the pump. If you have fuel pressure, but is doen't hold, check the fuel pressure regulator.
Was the fuel filter replaced when the fuel pump was replaced?
If you live anywhere that would have gotten gasoline from BP's Whiting refinery, you might have a case of bad gas from them. And it won't matter if you didn't buy gas from a BP station, as many stations will source fuel from other people. Our truck did the same thing, have you tried giving it some gas as you were cranking it? usually that will cause mine to fire up, but then you gotta kind of keep the revs up if it turns over.