I have a roper (whirlpool) top load washing machine. It will not fill with water. There is a good strong water supply & the screen is not clogged at hose. What could it be?

Bad water level switch or diaphragm, bad fill solenoid, timer or another part on the fill side. Could be just a loose wire. Open the control panel and start looking there.

If you want to fix it you will have to get a good digital multimeter, or even an analog meter, but a digital is better if you have never used a meter. Here are the manuals you will need: https://dl.dropboxusercontent.com/u/8010163/Understanding%20automatic%20washer.pdf
https://dl.dropboxusercontent.com/u/8010163/How%20to%20use%20Test%20Equipment%20Service%20Manu al.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool-Kenmore%20washers.zip
This is good, too:https://dl.dropboxusercontent.com/u/8010163/How%20to%20Diagnose%20and%20Fix%20Everything%20Ele ctronic.pdf
Go to Home Depot, Lowe's, or (expensive, but good) Radio Shack and find a good digital multimeter. A good meter will have automatic voltage protection in case you have voltage on a circuit when you have it set to "ohms." Make sure to ask about this feature. Others will have a fuse to protect the meter in case you have voltage on something, like a capacitor when you have it set to "ohms." On you washing machine there are three things that control water: The timer, the water level control, and the water valves. The water level switch has a plastic hose that goes to the bottom of the tub and to a diaphragm on the switch which operates a switch that has a common (incoming power) that is normally closed to send power to water valves. When pressure is applied through hose (You can blow on hose to test it.) the switch switches power from the water valves and sends it to a switch in timer to send it where it is needed. You can test all of this in a few minutes with a meter. No one can guess what is wrong; they can only tell you how to test it, and anyone who does it any other way is doing things wrong. You test first and then replace parts, not the other way around.