I want to build a selfbow out of a root.Is there anyone who has done it,know of someone who can help me.I've been building selfbows for 18 years.But have never did this.  

You'd be better off posting this in the Bowyer's Bench Forum.

When i first started thinking about making a self bow it was in the middle of winter and i didn't have any wood cut and dried.  However there was a great big pine tree that had been pushed over with roots lying all about the back yard.  So i started looking at them and noticed one that already had a slight resemblance to a bow.  I tillered the one side down and made a string for it.  I couldn't belive that it didn't break also it flung an arrow pretty decent.  My brother is still using it today.  He has about 30 yards of nylon kite string attached to an arrow that has no head.  He puts a tennis ball on it and shoots it for the dog.  The ball flys off the shaft after the string runs out and falls to the ground.  Sorry for being so long winded but it can be done.  I think if you get a decent piece of hickory or osage you might have something.  Best of luck worst that can happen is you put an eye out trying. lol just kidding i mean break it.