Can I appeal a disability insurance decision after nearly 6 years?

[sue in carolina]

What is the name of your state (only U.S. law)? South Carolina
Question: I had both short and long-term disability insurance through a major insurance carrier, when I became ill with a severe neurological infection in 2002. My disability from this proved to be long-term. My insurance company determined that this disabilty was mental, not physical, which meant that I received salary compensation for my short term disability, but not for long-term. At the time, I was very angry, but too sick to fight and was grateful to at least get the $579 SSI benefits, which my employer (or the insurance co.?) arranged on my behalf. Too, I'd rather assumed I'd eventually recover and return to work. This has not happened. In fact, I've since had to live largely off of credit cards and am about 5 minutes from being homeless. Do I have any recourse for appealing their 2003 decision (a mental vs. a physical disability in the wake of a brain infection) after nearly 6 years? Thank you in advance for your time to answer this.