Hello @Peter_Galvin1
Good to hear you found it, and thanks for coming back to say what it was. A lost network share is worth remembering as the first thing to check when a whole album vanishes at once.
On the pre-2009 purchases: Roon cannot play DRM-protected files, and there is no setting in Roon that changes that. The protection is enforced by Apple’s software, so the file has to be replaced with an unprotected copy rather than unlocked.
First, work out how many are actually affected. You may have fewer than you expect, since Apple upgraded a great deal of its catalog over the years. Protected files end in .m4p rather than .m4a, and in the Music or iTunes app the Kind column shows them as “Protected AAC audio file”. You can add that column from the View menu and sort by it. In Roon, they should also turn up under Settings → Library → Skipped Files, which gives you the list directly.
Then, the legitimate route is Apple’s own. iTunes Match is still offered, currently around 25 dollars a year, and it matches your library against the store and replaces protected purchases with DRM-free AAC at 256 kbps. It is the intended path for exactly this, and once the files are unprotected Roon will read them normally. The one limitation is that a track no longer in Apple’s catalog cannot be matched, so anything obscure may not be recoverable this way.
If a track cannot be matched, the remaining options are the ordinary ones: buy it again from a DRM-free source, rip it from the CD if you own one, or listen to it through a streaming service in Roon.
One practical step whichever route you take: once you have the unprotected files, replace the old ones in your watched folder, then force a rescan from Settings → Storage so Roon picks up the replacements rather than remembering the skipped originals.
We would steer you away from third-party tools that advertise stripping the protection. Beyond the legal question, they tend to re-encode and lose quality, and Apple’s own route gives you a better file.