I don't really know of many solutions to this, but to prevent losing game data...
Go to your player statistics when ever you boot up castle crashers or quit a game, if you don't have money, your characters, or any other items DO NOT START A GAME, once you start one, the game will save and your data will be lost.
If your data isn't shown from the player statistics screen, try some of the solutions Kelly mentioned.
Do not accept any game invites while in a game.
Hope that helps, can you do me a favor and click on my baby dragons? Lol.