Apologies, I had problems understanding your post. Perhaps your wording is at fault. LW Playlist which one? The LW program does not have a playlist. Quicklist is all it has. Perhaps you are mistaking the wording of what you mean by comparing it to another p2p program. I've used LW for almost 7 years but had problems understanding what you were talking about.

If the songs were still in Saved folder, simply drag & drop them back into LW's Library window. I've no idea why they would have dropped out of Library window by themselves without user intervention somewhere along the line with LW's settings or with the files themselves. Unless the LW preferences were somehow affected by logging off computer too soon after LW was closed (preferences not saved properly.)
I've removed my subscription to this thread, that should appease you. Considering putting you on my ignore list, that might be best so you only get assistance from those who can read. Done. We do this for free. Always other things I can be doing. Good luck with using LW 5.