Corrupted AIFF files on 2014 iMac

I have a 2014 iMac that is loaded with hundreds of AIFF files that I ripped from countless CD's. I haven't used the machine for a couple of years. I just got an M2 PRO mini and I wanted to move these files. However, when I opened the old iTunes app, ALL the tracks were grayed out. A dialog box said the files could not be found. Yet, they were all there, right where they were supposed to be. Two other audio apps also wouldn't open them as audio files. One app, Sound Studio, could Open, but not Play the files, saying these weren't audio files. But when I simply Saved the file (with no changes), the file was instantly recognizable to Sound Studio and iTunes.

Any ideas about what happened to these AIFF files? And, how can I fix them?



I asked this question awhile ago, but I got no response. If no one else has ever experienced this, is it something on my particular 2014 iMac?

Thanks, Carol