I highly suggest you consult with an attorney immediately. Based on the brief information you've provided, your former employer seems to have violated wage and hour laws, and may even be liable to you under tort law. You should consult with an attorney in your state immediately.
Your wage claim might be the only thing worth pursuing. I know what you are thinking about, a defamation claim. In reality, they can be a double-edged sword because when you sue for defamation you create a case where an issue that will be addressed is, 'are you a thief?' The fact that you aren't one may get lost in the process as you create the incentive for your formed employer to try to prove you stole. It's not likely to be a very satisfying outcome, even if you win. See if you can get some compensation out of the employer and that may be the best you can do.