I am french so my English isn’t perfect, I hope you will understand my problem.
I use Anki since the beginning of September ; everything is okay, but yesterday I wanted to create an Anki account to eventually save all the decks I put on it. But since I’ve did, all my decks disappeared and I don’t know how to bring them back, I find it nowhere, even not on my AnkiWeb account.
When I did the synchronization process, I have choose “download” but I didn’t understand the matter.
To restore from an automatic backup:
Open Anki, and choose Switch Profile from the File menu.
Click on the “Open Backup” button.
Select the backup you wish to restore from.
When restoring from a backup, any changes made since the backup was created will be lost.
The source of your worries was a sync conflict where you accidentially opted for overwriting your local decks (Syncing with AnkiWeb - Anki Manual).
To reliably back up your Anki content and other data (also for device defects, theft, etc.), you should regularly back up your storage medium to an external storage medium or a cloud backup service.
That’s good ! I was struggling because on Mac, you don’t have the menus at the top-left as on Windows, but I do the manip by keyboard shortcuts and I succeed to restore with my past backups.
I’m grateful for you having answer me - I hope my English wasn’t that poor.