I was level 26 just built the Irish bar and the observatory. Also just purchased $10 in donuts and was building Bart's teachers apartment and sent Skinner and Martin to the observatory and got the notification that they were done so I came back in game and POOF the opening scene played and I was placed back to level 1 and lost everything. Trying to find an answer is useless as this has been a known issue since December 2012. I want an answer and a game fix/restore AND I want my money back for my recent donut purchase!
Sorry for your problems. Getting a response from EA is pretty rare around here, and there is not much other users can do to fix real problems with the game/accounts. Good luck and keep reading other threads to see if you can find anything useful.
This is great as a solution if you have an android but sadly I have an iPhone. Next upgrade I won't chose an iPhone as I am limited with troubleshooting. It seems like a great option. Good luck to android users but sadly us iPhone folk still need a solution.