Those users [1] manually deleted their own media files. Did you do that?
If all you did was update Anki versions, that happens in a different folder than where your collection is stored, so that can’t be the reason you’re missing media files.
If these files recently went missing, have you already synced to AnkiWeb? If not, you should go to Preferences > Syncing > Log Out, then when you click Sync, you’ll log in again. That will trigger a rescan of media, and download any files that AnkiWeb has and you don’t.
I looked at the AnkiWeb account linked to the email address you used to post here. It doesn’t show any recently deleted media, so there’s nothing to restore.