Darkness

This is kind of weird. well first to the not so, when a plant has been in the sun or under some light source for 12 or so hours, then is in the dark is that when it grows, or does it grow while in the light. And this question os just for knowledge. How long can most plants survive without light? lol

my friend alredy did that with a 2 month old plant healty and shit , 3 weeks later all the liefs were finaly dead