In the Previous iTunes Libraries folder should be a number of dated iTunes Library files. Take the most recent of these and copy it into the iTunes folder.
Rename iTunes Library as iTunes Library (Corrupt) and then after you paste in the chosen previous library, it as iTunes Library.
Start iTunes. Should all be good, except for any recent additions to or deletions to or newly created playlists in your library.
Follow steps 1 - 2 -3 below
All credit goes to turingteST2
I've have never ever posted on a forum/help/discussion page before- but this worked perfectly for me
I'm still a bit sad that I've lost music and playlists added after the last recorded previous library -about 1 month ago - but overall I'm sooooo relieved that my music and playlists are back