A faulty pressure switch on your pump will prevent you from getting water from the well to your house. You should check the switch to see if you can find any corrosion or damage to the wires. A short in the switch will cause burn marks where the wires are attached to the switch. If you see this kind of damage, you need to replace the pressure switch. Replacing the pressure switch isn't that hard and most homeowners who are handy at repairing things can typically do it by themselves. If the pressure switch on the pump for your well has stopped working, here is how you can replace it.
There should be an electrical switch near the pump that you can flip to turn off the power to the pump and pressure switch, but that is not always the case. Sometimes, you'll have to shut off the circuit breaker in the house for the switch. You have to be careful unless you know for certain the circuit breaker is marked properly and you turned off the switch. You can't always trust the markings on the circuit breaker box.
Test Electrical Current
You should use a multimeter to make sure the power is off to the switch. Remove the cover to the pressure switch box by unscrewing the screw on top of the cover. Turn on your multimeter and set it to the AC (alternate current) setting. As you look at the top of the pressure switch, you'll notice one set of two wires connected to one side of a mini-divider, and another set on the other side of the divider. The incoming wires bringing power to the switch are colored black and the outgoing wires carrying power to the pump are yellow.
Place the red prong from the multimeter on one of the black wires and the black prong on a yellow wire. If the multimeter shows a current going through the switch, then the power is still live. You need to shut off other circuit breakers until there isn't a current.
Note: there may be a slight reading of .01 to .02, but that is just a residual current and it can be ignored.
Remove all the four wires connected to the top of the switch and pull them out of the switch. Place a pipe wrench on the water pipe the switch is connected to so you can keep the pipe from moving while you unscrew the power switch.
Buying New Switch
You should buy a new switch that has the same PSI settings as the old switch. To find the PSI settings, look under the cap of the old switch. There should be a label listing the PSI requirements for the pump. If you don't have a label under the cap, you should contact the manufacturer of the pump to find out the PSI requirements.
Install New Switch
Put plumbers tape on the end of the water pipe the switch screws onto and screw the switch back on it. Reconnect the wires in the same way you took them off. Replace the cover and turn the electric back on. The pump should work normally now.
For assistance, talk to a professional like Downingtown Electrical Plumbing Company.