Assuming your pool equipment is above the water line:
Start by turning off the pump, opening the strainer lid and emptying the basket. Check the basket for any cracks. If it is badly damaged, you may want to check your impeller for debris. If your Hayward pump is a super pump (square lid/basket) you can reach it from the strainer pot. Just poke a finger through the hole that the basket normally covers (PUMP OFF) and check to see if you feel a piece of plastic or a bunch of grass. Plastic = good, Grass = clogged pump.
Next, close your main drain and skimmer valves if you have them, put the basket back in and fill the strainer pot with water. Put the lid back on, open the valves, and turn the pump on. If the water in the pot doesn't move, you still have an impeller issue, possibly stripped threads. If it gets pulled down but no more water comes into the pump from your suction line after a minute or so, turn the pump back off and repeat the previous steps so you're ready to turn the pump back on, full of water.
This time, set your multiport to 'recirculate' or 'bypass to pool'. Turn on the pump. If you get water flow this way, then you've got a filter issue, may just need to be backwashed/cleaned.
Start with that and let us know how it goes.