last night, during a heatwave, my computer stopped working. So I turned it off and this morning, when I turned it back on again it had deleted all my files, and reset itself as if I had just unwrapped it. HELP!!
MacBook Air (11-inch Mid 2012), OS X Mavericks (10.9.1)
You may have logged in as a different user, such as Guest. Open the Users & Groups pane in System Preferences. Your name should be at the top of the user list, under Current User. See also this support article.
If files are missing from one folder
Change the Finder view mode; for example, from icon view to list view, or vice versa.