Statute of Limitations varies from State to State. Additionally there are different statutes or time periods for traumatic injuries, occupational and dependency benefits. You need to consult an attorney in your State.
Legislation usually mandates the time period a interpreted by case law.
California does have a statute of limitations for workers' compensation cases, but they are liberally construed in favor of the injured worker. There are many different aspects that you may be asking about, and I'm not entirely sure where your focus is. As a very general rule, if it is a specific injury (you fall down, get cut, etc.) you must report the injury to your employer within thirty days of it happening. If it is an injury that occurs over more than one day (like carpal tunnel, generally) you must report it once a doctor tells you that your injury was caused by work. if you have a dispute with the insurance company and you want a judge to resolve the dispute and award benefits, you must file an Application with the Appeals Board within five years of the date of injury or within one year of the last payment of benefits for you by the insurance company.
Of course, every situation is unique, and you provided very few facts to go by, so the above answers may not apply to you. The statute of limitations can be a bar to benefits if you wait too long, so you should consult an attorney quickly.
Workers' compensation cases in California have a statute of limitations. It is one year but it's complicated as to when you start to count the one year. If this is an issue for you, you should contact an experienced workers' comp attorney IMMEDIATELY. Find a good one here at www.avvo.com or at www.caaa.org. CAAA is the association for atttorneys here in California who represent injured workers.