Help... My water water pressure has been coming and going for a couple of weeks now when you use more than one facet/tub. My daughter calls me today to tell me the water has completely went out. What can the problem be?
The problem could be one of several. Likely causes are a pump that is bad or a pressure switch that has failed. If no one has been maintaining the system, it is possible that the pressure tank is bad and this has caused the switch or pump to fail.
Unless you have an understanding of how the system works and the ability to perform electrical testing, it would likely be best to call a pump/well company to diagnose and repair it.
cacher_chick is right, you have a pump or pressure switch problem. With the limited information it's impossible to diagnose your system. My recommendation is ask a friendly neighbor with a little mechanical ability to check it out then get back to us. Otherwise you must call a qualified pump installer.