Thin, volumnless hair.

My hair is so thin it just hangs there. I will only hold curl for about 2 hours if I'm lucky, but my biggest problem is that it look flat of top. I want to know how to add more volumn to my hair especially at the roots. I've tried all kinds of stuff from volumizing moose to the blow dryers that come with the prong things that are supposed to lift the hair from the roots to give it more volumn, but none of it works. Please help.Tara