ITunes :: After Hard Drive Change - Some Songs Not Available

I had an external hard drive that started to act wonky and wouldn't mount. I was able to get to mount one last time and transfer the contents over to a new hard drive.  Now every time I start iTunes there is a message about checking for gapless playback.  I believe there are 82 tracks.  It goes by rather fast so it is hard to read each and every title.  The ones I have read upon checking I find that the songs have no content.  They just don't exist. When you go to control I instead of the track showing the length it shows Not Available.