My chair disappeared.. Has anyone ever got it back?

Yes, many people have had their lounge chair icon returned. Something about your game triggered the game's suspicion for hacking, could be because of your big re-decoration. The only way to get it back is to ask customer support kindly for their help via the "help" button in the game settings. They'll have to confirm that no hacking was involved, and that may take a few days to a week. Respond to all email they send you. Don't send in a new help request until they've had a chance to respond, as that will just send your request to the end of the queue. Have patience and good luck.