If previously you were able to hear the fuel pump activating when turning the ignition key but you don't hear it anymore, there could be a problem in the circuit. Check the pump relay, wires, and connector. You may want to swap the relay with other circuits, just to test it. Make sure it is the same type. See if you notice any difference. Another test you can do: turn the ignition key to the on position and then turn it off. Do this about six times. Then try starting the engine. If it starts, the fuel system is leaking fuel pressure. This could be a bad fuel pressure regulator or an anti-drain back valve.