as the more you use it the worse things get. If your files are in the recycle folder then a "right click -restore" will do it. If they're not or the files were deleted by a program then Diodorus Siculus link looks worth a go. If the above does not work then you will need some serious data recovery software.
I have had results with GetDataBack click here on a very "distressed" drive. Before you buy recovery software phone the support people and describe your exact set-up. I advise this because some of the applications use low level drivers and the fact that your drive is external may matter.