Ok when you install a new version of LW or on a new computer, then LW must be closed when you copy across the downloads.dat & downloads.bak files. Otherwise LW simply ignores the information in them & uses what it was just previously. (such as empty downloads/incomplete folders.)

If you still have a copy of those such mentioned files then close LW, replace the newer ones with the old ones. Then re-open LW. Oh ... you may also need to replace the Library.data or something file in the LW prefs folder for that to work with newer versions of LW.