99% of the world energy supply comes from the sun. Without the sun, the temperatures would get colder and colder, killing off most life forms. First would be plants that need the sun for warmth and...
Technically, no; the Sun isn't "alive" as we understand life, so it can't "die". But it will, someday, change so completely that we might as well THINK of it as "death". The Sun is a medium-sized...