how long do i have to file a law suit after being terminated

It depends on what is the basis for the law suit.  Tennessee is an employment-at-will state which means you can be fired for any reason and there is no liability for the employer unless there is an unlawful motive for the action taken against you. There are generally only two forms of unlawful motives: unlawful discrimination or unlawful retaliation. Discrimination in employment is unlawful if it is due to race, color, sex, national origin, religion, disability or age 40 or older. Retaliation in employment is unlawful if you engaged in one of a handful of "legally protected" activities and were fired for engaging in that activity. If either of these was the motive for the termination, then you may have a claim for unlawful termination. Generally, discrimination claims must be filed within 300 days of the termination.  Some claims such as FMLA violations, certain wage claims, and certain racial discrimination claims have longer time limits.  You really need to speak to a Tennessee employment attorney who can help you figure it out.