Thanks for the reply. I don't think I explained myself correctly.
There's a long bolt, like 8 inches long, attaching the bar end. I unscrewed that and pulled it all the way out. Now, if I shine a light into the handle bar I see a piece of metal that fills the diamater of the handlebar; it's about six inches in from the end of the end of the bar. It has a square shaped hole. Then, just beyond that, I see a square shaped nut turned sideways.
I assume that I somehow I pushed the nut out of the square hole, and now I have to get it back into the hole so that it can accept the bolt when I put it back on. I did try tipping the bike but the nut did not seem to want to move.