(1) Check the electrical breakers in your breaker box. Check the
reset button on your well control box. Check the water shutoff
valves at your well and on the main line into your house to make
sure they're not turned off. If none of these is causing the problem...

(2) FIRST, TURN OFF THE POWER TO YOUR WELL.
Then, check the contacts in your well pressure switch to see if they are
either dirty or otherwise prevented from functioning properly. You may
find that ants or a lizard caused a short circuit to occur. If the contacts
are corroded, you can clean them carefully with an emory board.