If your are just getting a click, that is the starter solenoid working, but the starter is not turning over the engine. You might try tapping on the starter with a hammer ( if you can safely do this ) while some one is cranking trying to crank the engine. If the starter begins to work, then you need a new starter. This is assuming that your battery is still powerful enough to turn over the engine. A fully charged battery can still not have enough power to crank an engine over if it is old and worn out. It can still operate the lights, but that is minor compared to the energy needed to crank over an engine.