For a claim of discrimination, you have 300 days in which to file your complaint. If you fail to file within that time, generally you lose the right to make any complaint at all. Other claims may have shorter time allowances.
If you have accepted a settlement for termination and signed a waiver of rights to file a complaint, you may have lost the right to bring a claim.
If you feel you have a legitimate claim against an employer, it may be best that you talk to a lawyer who has experience in employment law. It takes time to prepare and file a claim so don’t lose your rights due to waiting too long.