Q: Latest update deleted my library and playlists

Generally if you restore an old library file as described in  Empty/corrupt iTunes library after upgrade/crash then even if some items aren't listed, those that are will play, importing the remainder isn't too hard, and the library will be recognized as the home library for the device.

I have a script called FindTracks for repairing links when iTunes cannot do it by itself.

Since iTunes is now shown as a new library see Recover your iTunes library from your iPod or iOS device. There are some scripts listed near the end that can recover ratings, play counts and playlists.

See also Make a split library portable. You may want to make sure you are rebuilding your library in a way that makes it easy to backup and migrate in future.

tt2

Well, I managed to get all of the music back in, but there are still a couple of voice memos missing.