For Where Art Thou Sister

Yesterday, October 09, was my sister's birthday.
She turned 46 years old.
No one in my family knows where she is or has been for the last few months.
She has, for reasons unknown, successfully vanished entirely from our lives.
She will not answer emails. She has moved without telling us so of course we do not know where she is living now. She changed her phone number. Turned out that none of us had her work phone number nor did we know the name of the company where she worked!
I know it sounds strange now but she and I were not close. She would never return my phone calls when I left her a message. She would only call me when she needed my help. She and our brother were not close either, so I don't think they spoke on the phone at all. But I was shocked to find out that our mother didn't have her work information. Especially since I knew she has talked to my sister during the work day many times. When I asked my mom about this she said my sister would call her from work but block her work phone number. How odd. Even odder that my mom never mentioned that or the fact that she didn't have my sister's work company name till my sister went missing.
My sister has always had issues. She's had nervous breakdowns too.
There have been times when I've watched her dog for a weekend and she's come to pick her up and then my sister will act like she extremely pissed off with me. It's hard to deal with.
But she is my sister and I love her and I miss her. I hope she is okay and well and that one day she will come back.
Our mother thinks she came into a lot of money and this is why she has disappeared. My brother thinks our sister disappeared because our mom can no longer help our sister financially.
Me? I had a theory but I am no longer going to pretend that I have any idea what is going on in her head.
Happy 46th Birthday Sis! I hope it was a good one where ever you are.