I accidentally tried to rearrange the note type of my cards in Anki Desktop, and afterwards the field that previously contained my images is now empty.
The important thing is that I have already created and updated many new cards since then, so I absolutely do not want to restore an old backup and lose those new cards.
I checked Tools → Check Media, and Anki reports:
“The following files are referenced by cards, but could not be found in the media folder.”
However, I believe the original image files may still exist somewhere in my Anki Desktop folder. I did not intentionally delete the images or the notes — I only changed the note type. I also didn’t find any medias in the bin of my computer.
That is the section about “Missing” files, which doesn’t sound like it would apply to your situation. Does it also report that you have “Unused” files? If so, those files are still in your collection.
If you deleted that field from your note type, that would delete all of those references to your files in those fields. The references would remain lost even if you later re-added the field to your note type.
Is that what you did? Or did you use Change Note Type to switch these notes to use a different note type? The methods available to restore are different depending on what you did.
Do you know approximately when you made that change?