Even if the incident you want to complain about resulted in your termination from employment, you're probably a long way past the "statute of limitations" which limits how long you can wait before filing a successful lawsuit. You should check with an employment attorney to make sure, but you've probably waited far too long.
Even if this incident were harassment, which it dosen't sound like, you've allowed the statute of limitations to expire by waiting this long.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.