I suddenly find that I no longer have access to most of my music without buying downloads again.

When I look at my purchase history what I'm seeing is the price I paid at the time, not a price to download them. Your unhidden purchases should show up with cloud links in your library that allow them to be streamed or downloaded. You need to be signed into your Apple ID and have your computer authorized for this to work. Also make sure that View > All Music is ticked. When you first try to play or download a past purchase you may get a prompt to associate your computer which locks it to that ID for 90 days. Regional iTunes stores operate independently. To retrieve purchases made in the french store would require another association, so you'd have to wait for an opportunity to download those items, or use another computer.

tt2

Ideally you would have kept backups of all of your purchases. See Hide and unhide music, movies, TV shows, audiobooks, and books - Apple Support and check to see if anything is hidden. Have you made use of more than one Apple ID?

tt2

I can see my purchase history back to 2007. Are you sure you've only ever used one Apple ID?

Initially iTunes songs were sold on a one download basis with DRM and the onus was on the user to maintain a backup of their purchases. At some point DRM was dropped, and repeat downloads were enabled, however with past purchases there was always the risk that the ability to redownload might be lost if the rights holders removed the content from the store.

I'm not familiar with any view of the library that would show your purchase history but then demand payment if you tried to play or download items. Where exactly are you seeing this?

tt2

You're welcome. 🙂

tt2