Winamp can help you put the albums back together and identify the mess iTunes has made, but you will have to do the hard work of moving files around.
I have often cleaned up iTunes folders salvaged from a hard disk by using Winamp to put an album together again. The main thing I use is to add an extra column to the Winamp Library View of "File Path". Then I can see where an album has been scattered to.
Most of the problems are in the "compilation album" folders. So not as bad as it initially looks.