[fred bomber]

I had the same problem and the rovio support recovered my progress (but it takes 3 days).
You should send a request here: https://support.rovio.com/hc/fr/requests/new (sorry it’s the french version but you can find your local site by searching rovio support with google). You should send your facebook ID to win time (you will find it in facebook: settings/ apps/angry birds 2 and your Id is in the bottom of the window that appears)

[fred bomber]

I frequently have the same problem and I uninstall and reinstall the game when it happens. Then I log in with my facebook account and my progress is restored. But the last time I did it, I lost all of my datas.