Lost all my decks trying to sync from Web to App

I had Ankiweb, and then downloaded Anki for the mobil app and tried synching my things from Web to my the app and I lost ALL my decks. How do I get it back, can I? I need this for school, I had all of my study things on there…

If you accidentally synced in the wrong direction, you may be able to recover from an automatic backup: Restoring an Automatic Backup (Recovering from Data Loss) - Frequently Asked Questions