If Emacs or the computer crashes, you can recover the files you were editing at the time of the crash from their auto-save files. To do this, start Emacs again and type the command M-x recover-session.
This command initially displays a buffer which lists interrupted session files, each with its date. You must choose which session to recover from. Typically the one you want is the most recent one. Move point to the one you choose, and type C-c C-c.
Then recover-session asks about each of the files that you were
editing during that session; it asks whether to recover that file. If
you answer y for a file, it shows the dates of that file and its
auto-save file, then asks once again whether to recover that file. For
the second question, you must confirm with yes. If you do, Emacs
visits the file but gets the text from the auto-save file.
When recover-session is done, the files you've chosen to
recover are present in Emacs buffers. You should then save them. Only
this--saving them--updates the files themselves.
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