After upgrading iTunes to 12.1.1.4 (around 2/25/2015), my library has reverted to a version from 12/28/2013.
None of the "Previous iTunes Libraries" or .tmp files are newer than the 12/28/2013 version.
All of the media files are perfectly fine and in their normal location.
Can I restore my "iTunes Library.itl" file from my iOS device?
Windows 7
I suspect you have been attempting to access the previous libraries in a way which always shows you the same content. See Empty/corrupt iTunes library after upgrade/crash for advice.
Otherwise see Recover your iTunes library from your iPod or iOS device. You can import any missing media from the media folder into the library. There are some scripts mentioned towards the end of the recovery tools section that can rebuild ratings, play counts and playlists.
tt2
Can I restore my iTunes library file (iTunes Library.itl) from my iOS device?
