You should check the electric for power to the pressure switch, then the well. Then check the power cable for no shorts or opens and then the ohms of the pump motor windings. www.franklinelectric.com has them.
If you have a 3 wire type pump, you'll have a control box by the pressure tank in most cases. It could have a bad capacitor or relay. Franklin will tell you how to check it.
You could have a power cable that has shorted or a leg open. Or the pump motor quit. Or the thermal overload opened for some reason and shut off the pump. You could have a low pressure safety switch and have to lift the handle to get the power to the pump (or control box) and then when the pressure is above 20 psi, let go of the handle to reset the switch.