Last weekend I experienced a similar problem.
Starter wouldn't turn over or make any sound. Battery, however, showed 6.3 volts. Long story short, when the battery was tested under load at the parts store, it died immediately. New battery fixed things right up.
Have you tried to jump start the truck or connect a known good battery? Even a twelve volt battery can be used to test your starter. Don't turn anything else on, though.
