Generally, exhaustion of your administrative remedies for Labor Code violations are not a requirement for filing a civil action. Assuming the statute of limitations is not expired, you can file a lawsuit in Superior Court regardless of the DLSE decision on the merits. While the denial of your retaliation claim by the DLSE may suggest that your claim is not strong, the DLSE has little incentive and time to investigate the facts as thoroughly as a private attorney. Do not let the DLSE's decision discourage you from speaking to an attorney regarding the evidence and filing a lawsuit. If you blew the whistle on regulatory or statutory violations and then suffered a retaliatory termination, you could have a common law claim for wrongful termination (a "Tameny" claim) and statutory claims under Labor Code sections 1102.5 (whisteblower), 6310 (Cal. OSHA) and/or 98.6. Good luck.