It was something like this, I had updated the game for halloween event. When the halloween event didn't show up in my game, I cleared the cache on chrome, after that I've logged in and lost the progress. Then i read on the forum to reinstall the game. I tried the advices and it didn't help. I was playing only on one device.
I've been playing the game for about 3 year and never had a problem with save file. Progress should be backed up on my facebook, it always was. I'm not getting any error messages. I simply log and there is level 1.