There are conditions under the server file cleanup policy where if you are offline over a period of time, the server can delete some of your stuff, like inventory, ender chest contents, and even your balance and set homes. However, if you meet certain criteria, these kinds of things may be saved. Check out that link above for detailed information.
Other than what OnScene mentioned above, there are never and will never be money resets. At least, never sever-wide.
