There is a white exclamation point in a grey circle to the gone of respectively of these song titles that won't play.
Answers: yup. you'll enjoy to navigate to your user folder surrounded by My Documents, later Music, next itunes, after your Lib, next the fastening folder, later the album, later the song
you may enjoy renamed some songs and not did it properly or moved folders or music
this medium that the wallet be most credible thrown away thats what usually happen. If your lucky, check the trash and remove the files and put them into a folder. If not later you own lost them