Have been running earlier version for years. Apparently this version was installed yesterday so I believe I must have clicked to update to latest version, though I don’t recall doing so. No LO files are open in Task Manager.
Which OS do you use? Why do you think Task Manager will open LibreOffice files?
Try to open LibreOffice first and then in LibreOffice select File>Open. Find the file you want, mark it and click OK.