Itunes updated unexpectedly and lost all my favourites and playlists

gambleruk

About a month ago I opened my Itunes and it had updated, I have not updated it for years as only use it now and again mainly to add songs to my favourites for the year.

Once it had updated everything had disappeared and was just like a new install, so I reloaded my library but that was a disaster as songs, tiles and album covers were missing or duplicated, I then used my backup itunes music folder which did a much better job (still missing some album covers) but I am still missing all my playlists and all my songs I have starred from 1 to 5 over the years.
There are about 16,000 songs in there so as you can imagine I really do not want to start afresh.

Anyone any idea first of all why it updated after all these years ?

Secondly is there a way to go back to my original itunes so all my album covers reappear etc or is that lost for good now ?

And finally is there a way to import all my playlists and favourites back with one click or do I have to do each one separately ?

Thanks in advance for any help.