iTunes Library Disappeared/Regressed

[Gothamoddisee]

I returned home today to find that my iTunes was missing nearly all of my playlists, all of my podcasts and a great deal of ratings and tracks! I ran a search for iTunes Libraries and found one other besides the active one. I replaced the broken one with that one, but now I'm using an iTunes Library that's a month old. Ive added a lot of music and playlists since then. My 2 questions are:
A) Is there any way to find a disappeared itunes library which seems to be the case here?

B) If not, is there a way to make sure that all of the tracks in the music folder are showing up in iTunes without importing the whole folder again, forcing myself to sift through perhaps millions of duplicates?

 

[eric2006]

I'd be odd for your library to just disappear, but one thing that could have happened is that you inadvertently changed a character on your userfile, and OS X created a new user. Looks in /Users to makes sure that there is only one file per user. Make sure that there is only one iTunes library file in /Music. Where did you find the old library file?

 

[Gothamoddisee]

Actually, I found the newer iTunes Library in the Previous iTunes Library folder. And unfortunately OS X did not create any new users. So that doesnt seem to be the cause of the problem.