First you must ascertain whether the power is actually getting to the switch, Mary! If so, the switch can be checked to determine if it is at fault.
It is almost imperative to have a multimeter for checking these electrical power problems and today's digital multimeters are very easy for amateurs to use in such cases.
It is often required that one has to work backwards from the problem to find the answer. Check out my RV article concerning using a multimeter for more info on tracking down RV electrical problems.