when you changed the water the wet end of teh pump became empty of water and when you filled it you should have put the hose into the filter pipe to get water back into the pump.
In other words, you have an air lock, and the pump is not moving water through the plumbing to come out of the jets.
Loosen the union on the pump, or one of the drain plugs. You will hear air rushing out until it fills again with water, tighten and your done.
