See my reply to your first message. There's some info there that will help. I think you might have been drawing with the wrong mode with the Pen tool, making one end of the path pointed and the other end wider.
However, if it's a regular bezier path, you can increase the width. Object menu > Fill and Stroke > Stroke Style tab > Width
Although....if this is regarding the file you attached in your first message, there are no strokes in that file. The outline is a compound, closed, filled path. It could be made wider by adding a stroke. But that might not work, depending on your end goal for the drawing. So if this question is for that file, we might need to know more about your goals, to be able to give you the best answer.
