legal advice

If you have been dismissed without a proper reason and or you were fired because of issues like discriminations etc that means you can be a victim of unlawful firing case. And if so, you can challenge it.
The bad news about this is that the laws about this vary from state to state. So, ideally you should consult a lawyer about this. An other factor is that this entire process is quite time and money taking.
But in case you win the case, you are likely to get fines and salary and other compensation money etc.
A very important point is to be taken care of and that is what type of employee you are. If you are an at will employee, your chances of winning are very less as your employer will always have the right to fire you without any prior notice and decision.
In case you are a for cause employee, things can work for you. If you are fired, you can challenge your firing decision easily and the chances that you an win are good too.
If you a member of some union, you can file grievance for the review of the things happened.
Those who are government employees, generally have some property inertest in the job. They can not take away without any proper reason mentioned in law.
But if you are not a government employee, you can file a lawsuit. Being an employee, you are entitles to be paid back the wages, reinstatement and inertest etc. So, you should understand what your privileges are as an employee.