I was working on an InDesign file earlier today and had saved it multiple times to the the desktops folder under This PC, and I left for a while, and when I came back, the session had timed out. This was expected, but when I tried to reopen the file, I couldn't find it anywhere in any folder. What might the problem be?
Can you open it from the Recent File list? What do you mean by "session timed out"? InDesign doesn't time out.
Are you working on a network? That is the only thing that might make sense about the "Session timing out". If so then contact your network administrator to see if there are network backups to files.