Tank you for your answer.
Under the “public/system” directory, there are the 3 folders: “accounts” “media_attachments” “preview_cards”. Inside, i have a lot of sub folders with avatars or media.
Yes, all the “live” directory was deleted before the reinstalling (the directory where my instance is installed). I did not restore the “live” directory after the installation because the instance seemed to work properly. I only restored the database from the backup.
I thought that the missing avatars were going to be loaded later from the other instances, but it was not.