Ask Max: Are men from outer space mickeying with my Mac?
I came home after being away two days to discover my documents had disappeared from the document folder in my dock. Instead when I open that folder I get something that tells me about Stacks. But nothing helpful for retrieving my documents. Not only did this happen, but the icons I had dragged onto the screen, things I was working on, had also disappeared.
I have had such a time getting used to the iMac and find it really disturbing to have someone from "outer space" mickeying with what's on my own computer. I don't want everything updated and changed every five minutes. Am frustrated enough to consider sending this thing back and returning to the despised PC.
From your description, it sounds like your computer rebooted into another User account. Do you have multiple user accounts? Try checking the "Accounts" section of your System Preferences to see if you have two accounts. Then change the "Automatic Login" to the proper account in the "Login Options" Section. Enter your password and restart the computer.
This is most likely what has happened. I hope this helps. And stick with the Mac. The additional problems you'd have with a PC will have this small issue pale by comparison.