Zapisałam plik ze wszystkimi stronami, następnie zamiast zaznaczonego tekstu skopiował mi się inny fragment, a nowe stron usunęły się 
Hello,
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How do I restore a lost version of a job?
I saved the file with all pages, then instead of the selected text I copied another fragment and the new pages were deleted :
As soon as I do something wrong I click Undo or CTRL+Z. If it goes horribly wrong and I haven’t saved the mess I can go back to the last save by clicking File > Reload
If you have saved the error, there is a chance that you might have a backup saved. To see if you have set backup to be saved go to Tools > Options > Load/Save > General and see if “Always Create a backup copy” is ticked
If a backup has been created you can find out where by in the same window, going to LibreOffice > Paths and using the path shown to find the backup in your file manager. For me, it will have extension .bak
