How to reset ecu after changing fuel pump?

You shouldn't have to reset the ecm after changing the fuel pump. Did you check the fuel pump fuse? The fuel pump relay? Did you verify that you have power going to the fuel pump? Did you check the ground at the fuel pump? I would get a wiring schematic and a voltmeter or a test light and check these items. The ecm doesn't need to be reset so you have a different problem and you could have gotten a defective fuel pump so you need to verify that you have power and ground at the fuel pump. And the fuel pump will only turn on for 2 seconds when you turn the key on just to prime the line after that it will turn on after you get oil pressure when you crank the car over and after it starts.