I synced my desktop decks with my Ankiweb decks and got that popup asking me what to overwrite. I choose to overwrite the decks on Ankiweb because I assumed only the cards with conflicting options would be overwritten. That was not the case and my decks that were previously on Ankiweb are now gone and are replaced by my decks on desktop.
How can I recover those decks? I know from other discussions that Anki creates backups, but as far as I can tell the backups are only made of the decks on desktop, not on Ankiweb.
I am afraid that there is no automatic backup for ankiweb
Have a look in the FAQ section Restoring an Automatic Backup (Recovering from Data Loss) (sorry, cannot publish a link here, the forum software refuses links)
Maybe you have some data set in your local backups to restore