will not start seems to be fuel delivery or maybe something electrical on 2006 Nissan Xterra

It seemed as if it ran out of gas so i put some gas in it now it still will not start i have check fuses and relays i pull the fuel line off i know the fuel pump works the spark plugs were pretty burned out i repaced those i dont know what else to check please help

Asked by for the 2006 Nissan Xterra
You will need to verify that the spark plugs are firing and the fuel injectors are opening. Can you do this?