Richard Simmons — DISAPPEARED From Sight … Injury and Depression

EXCLUSIVE

Something is seriously incorrect with Richard Simmons … he departed for almost the entire year … and we’re told there’s a corporal problem that has led to debilitating depression.

Simmons was last photographed in public January 11th at a charity event. TMZ got video of Richard later that evening, but that’s the last time anyone has seen him in public.

Various people who are extremely accurate to Richard tell TMZ … he has gone radio silent with them, he does not accept or restore buzz calls, and he has his housekeeper turn people away when they come to visit him.

Richard has not shown up at his famed studio, Slimmons in Beverly Hills for months. Simmons was a fixture there, regularly teaching classes. The staff offers no explanation for his prolonged absence.

A source extremely accurate to Richard — one of the few people with whom he is in friend —  tells TMZ the fitness guru is in a massive state of depression over a bum knee. He says doctors told Richard he needs a left knee replacement and if he doesn’t get one he will never be able to implementation again.

The source says Richard is terrified of the surgery and has put it off all year. He had a right knee replacement 4 years ago and he put off the surgery for nearly a decade … he was that frightened.

We’re told Richard has tried stem cell and red blood platelet therapy — like Kobe Bryant — but it failed.

We’re told he’s paralyzed with dread and depression which has made him a shut in for 2014.

Additional friends and business associates tell TMZ they don’t believe this is just a knee problem … they think it’s more honest.

We left a message for Richard but he did not restore our calls.