If you can't press Ctrl+Z to get it back (Undo, assuming you haven't closed the document), then when you save documents, it saves temporary files into the same directory on each save, that are deleted automatically when you close word (sometimes they stay).
Goto Tools > Folder Options > View > and check 'Display hidden files'
There should be a bunch of similar files (but marked as hidden) to your word doc. Find the last one before you saved, and rename it to .doc , open it and see if the content you want is still there.
If not, try another one. You may not have temp files you haven't saved it before you stuffed it up.
Hope that makes sense heh.
Med