how continue a path from one point by using pen tools in illustrator?

I use pen tool to draw around of shapes in my sketch in illustrator , during drawing I do wrong and the path is closed , I want to continue from one point of this path but I don't know how do it by pen

here is a picture of my probelm

Answer

If the file is still open, follow OghmaOsiris' answer.

If the file was closed and/or undo is not available, use the *Direct Selection Tool * (White arrow) to click the section of path you do not want, and then tap the Delete key. Only that section should be removed. You can then use the pen tool to click one of the end anchors and continue drawing the path.