I am going to send you the information for a popular top freezer Whirlpool and this one is the most complicated Whirlpool so other models have fewer parts to remove. Save this page to your favorites so you can return if you need to return and if I happen to hit the correct model then that would be super huh. Anyway let me know.
Your defrost drain is clogged. Instead of the water going down the defrost drain in the freezer its going through the freezer floor.
Unplug the refrigerator from the wall outlet. In the freezer remove the screws in the panel with the blue arrows. That is the freezer floor.
Loosen the 2 screws over the top of the ice maker then take out the one at the bottom of the ice maker if its there. Lift the ice maker off the 2 top screws and follow the wire harness to the back wall. Unlock that and pull the connector. Take out the 2 screws you loosened.
Then remove the parts with the red arrows. That is the back wall and airflow duct.
Behind those parts is the evaporator coil
that defrosts about every 10 hours. The drain for the defrost is in the floor directly under those coils, its just about the size of a dime. Dig out all the ice and clear that hole.
Once you get that done pour a little warm water down it to be sure its clear. If its not clear find something flexible and push down through it a couple of inches.
Go around behind your refrigerator and remove the lower panel then find the tube that comes out just over the drain pan. If there is a small amount of water in that pan you will be done. The water that drains into that pan evaporates.
That will take care of it, if you have further questions please ask.
CLICK TO ENLARGE