I own a facility where people pay us to keep and care for their horses. We run a nice, clean facility that people come to and never really leave. Most of the people who keep their horses with us have been here 10 or more years. We know each other very, very well. 
One of the ladys who keeps her horses with us comes out 6-8 hours a day Monday - Friday. She has 2 horses, is retired, lives alone and never comes out with friends or family. She has never provided us with emergency contacts for her or her horse. She has been here for 13 years, never made a late payment and only misses days when it is raining really heavily. She is extremely quite. I can honestly say that I know very little about her beyond our "horse life" together. She has been missing since March 6th. No one has seen her. She missed paying her rent on the 15th (which is totally out of character - she normally pays on time or early,) and she left blankets on her horses because it was raining around the 6th, but now it is 82 degrees - this is also totally out of character. (I pulled the blankets off for her.) 
- she has no family or friends that we know of to contact
- I don't have a driver's license number
- I have her address and telephone number but the sheriff went by and she is not there and she is not answering her phone
I have called the sheriff and had them do a welfare check on her. Her house was locked up, with a package on the porch. Neighbors have not seen her and many phone calls have gone unreturned from me and her small group of friends out here. This is not a woman who would just leave her horses behind. This is not a woman who would leave a bill unpaid, even for a day. This is not a woman who would leave blankets on her horses so that they are overheated in the sun. 
Tomorrow I will be filing a Missing Person Report with local law enforcement so they will begin checking local hospitals and jails (highly unlikely,) and be allowed to go into her home to check on her. 
I'm worried about this woman who has been in my life for 13 years. She has an old, blind horse who is terrified of everyone but her - what is going to happen to him if she doesn't come back? I'm so worried. I can't think of any good scenario that would keep her away for this long. 

How does someone just vanish into thin air? Anyone have a similar experience with a happy ending? Any suggestions of something else I can do? She has no social media accounts or anything - we are talking about a modern day hermit here. Ugh. 
***UPDATE*** 
The sheriff found her last night at a local hospital. After several phone calls we learned she had a systemic infection and had been hospitalized since the 7th. She is on the road to a full recovery, but will likely be in the hospital for a few more days. I'm just so thankful she is okay! (Can't lie, partially because now I don't have to be the one to handle her horse!) 
I'm fine. Sore and achy, but so relieved it makes up for it!                 
Re: Missing Person - Update
It seems very out of character for her by what you are describing.
Unfortunately, I would lean more towards the thoughts she passed away and is in her house. I'm really surprised the sheriffs department did not get into her house to do a welfare check. Sorry to be grim and hopefully this is not the case.
No one that you know of has a key to her house to allow law enforcement to go in?? Possibly a neighbor. Hopefully after the missing person report the department will do a little more follow up.
Also ca law states there is no waiting period to file a missing person report. So if you want one the department must take report so don't let them tell you no.
But honestly, if she hasn't been seen since at least the 6th, that's a really long time.
I hope she's ok. Thinking and praying for her.
She is an extremely private person, so I didn't want to push too hard too soon, but I really feel like she must be in a desperate situation at this point. We do not know anyone with a key to her place. There is a landlord involved but he wants the sheriff to demand to be let in, (which it looks like will be happening this afternoon.)
The sheriff we are working with also keeps his horses with us and knows her too. He agrees that nothing good is going on here.
And then we are talking about her like there is no chance she is okay. That makes me so sad!
I just feel awful. I should have made her give me an extra number for someone else to call for the horses at least. I have no idea what to do at this point.
DD2 8.22.13
MMC 1.4.17 at 16w
Expecting #3, EDD 1.29.18
I hate to even mention this, but someone told me the reason this lady, (lets just call her CeeCee,) was such a hermit was because she was violently attacked when she was in her mid thirties.
(edited due to toddler help.)
DS born 9/3/13; DD born 7/22/15; LO due 5/28/18
FS (age 5) and FD (age 2) to become AS/AD very soon!
Nora Grace Due 12/26/2016
Two Angel Babies
07/03/2012
08/08/2015
"If you're still my small babe
or you're all the way grown,
my promise to you
is you're never alone.
You are my angel, my darling,
my star...and my love will find you,
wherever you are."
I have been at the ER for the last 6 hours and have a fractured facial bone. Sooo... that was fun.
Today has been pretty shitty.