Restores a lost notepad++ session as initially described here: https://superuser.com/a/1499453 (original author)
Reads all opened files from notepad++ backup folder and creates a new session.xml in the current working dir. This only works if session snapshots had already been enabled before you lost your session. See Settings -> Preferences -> Backup
Copy the generated restored_session.xml and overwrite the existing session.xml in %APPDATA%\Notepad++\.