Money and taking extended breaks
I took a very long break from July last year to September this year and didn't lose anything. So I can say that money doesn't disappear, though I can't say why yours did. Sounds really weird.
Forum Discussion
Maybe your town was hacked? Recently, the game had a bad glitch, where a lot of players were being signed into the wrong towns. I know, several months back, the same thing happened, and some players were reporting that, whoever got into their towns by the glitch, were being stinkers, and nuking the town they were in. With the recent glitch, maybe someone did get into your town by mistake, and decided to blow all of your money. I guess the best thing you can do, is try to contact EA, and get this issue resolved. They have logs and all the information on everyone's towns, so maybe they can check and see if someone spent all of your money really fast.
