For the past 2 days, I've been listening to this great podcast called Missing Richard Simmons by Dan Taberski. In it, Dan explores the odd disappearance of Richard Simmons (who has been missing for a few years -- at least in public -- and the unfortunate people/friends Richard has sort of "left behind". It's a tragic story with a few really interesting twists. I would highly recommend subscribing. New episodes are still coming out weekly.
The New York Daily News has published this longform article about the mysterious disappearance of Richard Simmons from the public view and the very scary reality that he may very well be locked up in his own house and suffering from a mental breakdown.
The article mentions several close friends of Simmons who have not seen him in person for over 2 years.