If you have a copy of the old Downloads.dat & .bak files, replace the newer ones in the incomplete folder. This must be done whilst LW is closed.

I have no idea why you are not seeing incompletes in the incomplete folder though in the LW Library window. Whether they are being utilised or not by LW you should still be able to see them. Only thing I could think of is either your download location changed, else if either permissions changed for that folder that disallow you access to utilise the files in it.