Your employer changing your employment records does not constitute a wrongful discharge unless they did so because of a protected characteristic (age, race, gender, religion, national origin, etc.) or in retalliation for your exercising your protected rights, such as filing a worker's comp claim, making a good faith complaint to a gov't agency such as OSHA, etc.
If sounds like you need to call your State's Department of Labor and/or speak to an attorney to explain the full circumstances or your separation and determine whether there is any legal basis to file a complaint with the State or initiate a suit. If there is, then you need to ask about any statutes of limitation that apply.
