Hi GolfGal722
Drew Reece is right - I used the advice from double-ohh7 on page 1 of this thread - https://discussions.apple.com/thread/4666718?start=0&tstart=0
and it worked perfectly - on my old MacMini and on my new iMac.
as far as losing your songs goes - try this.. (and sorry if you already know all this..)
open a new finder window (click on the desktop and type Command-N)
a new window appears.
in the top right hand corner is a Search field, - type in the name of one of your lost songs
a list appears in the window, and hopefully one of the items in the list says the name of the song, probably with .m4a or .mp3 after it.
click once on the name of the song and a list of folders will appear along the bottom of the window.
you might have to expand the window so you can read the folder names, but you will see that
(a) the song hasn't been deleted, it still exists
(b) if you double click the song name, that song will start playing, and is now visible in iTunes
and
(c) if you follow the list of folders, you can see where it (and all your other songs) are.