I had this problem before, and I was told how to recover, but I can't find the posts. If I search for my handle, it shows like 4-posts, when there are many more.
I'm using SE 2013, v18.0.0.13, 64-bit. I have enabled "One File per window".
I split a window to edit the same file in two places, then hit some unknown key sequence and one of the windows disappeared. SE would not let me open another window of the same file. So I clicked "One Window", which was a mistake last time and this time. Now all the files are gone and all the tabs across the top showing each file are gone. I poked around and clicked "Toggle Zoom", which brought back the one tab for the one file that being shown. The other files are still open. How do I get the tabs back?
Steve