Find and check the circuit breaker for the pump. With any electrical device always check the circuit breaker first, this may be an easy fix if the breaker just needs to be reset.
Look for obstructions around the water pressure switch by removing the cover protecting the switch and see if there is any debris or other item that may be preventing the switch contacts from being able to close.
Low Water Pressure
Open the valve that drains the tank, if there is a low water flow it may indicate that the blades on the water pump may be worn after years of use and they are no longer capable of maintaining a good supply of water.