this works for me because i have my other (2nd) mac with the same library setup
1. delete all the files in the itunes previous library except the latest one
2. export the library from my 2nd mac : itunes, file, library, export library (.xml file)
and transfer the library file (.xml) into my mac with itunes problem to its desktop
start itunes (no songs)
then go to file, add to library and just find the the .xml file on the desktop
hope this helps.