Why has a calc file, suddenly converted to a writer file?

I have a document saved as a ‘calc’ file, use it all the time and today when I tried to open it, it suddenly opened as a nonsense ‘writer’ file, full of YYYYYYYY. It shows I have 4326 characters, so the data is obviously there, but is completely unusable. I really need this file, so would welcome a solution ASAP. Cheers

There is no “calc” file but ods, fods and various other formats and files do not change their respective format “all of a sudden”. The only thing that might happen (e.g. through an update of the operating system) is a change in the the association of a file names extension (eg. .ods) to a spefic application. So the question is: Have you ever tried to start calc and then use File -> Open and having selected the file from the file picker dialog? Don’t use explorer and just double click on the file. If this action opens LibreOffice Writer the the most probable causes are

  1. The file has no extension at all and LibreOffice is somehow the default application to open files
  2. The .ods file type is no longer associated with LibreOffice Calc (most probable)

Welcome to the world of hard disk failures and/or operating system crashes eating precious data files.

Restore the last known good version from your backups that you hopefully did more or less regularly.

By chance you also have the LibreOffice internal Always create backup copy enabled under Tools → Options → Load/Save → General, if so then look in the Backups path specified under Tools → Options → LibreOffice → Paths.

If all else fails, try un-deleting temporary files

Not sure I did the back-ups I should have - doh! I have gone into Tool > Options > LibreOfice - Paths and I can see Backups - but do I then click on reset? Or default, edit? So odd that some files are still opening OK and others seem corrupted and are just showing YYYYYYY. This seems to happen after I had opened an excel file and I don’t have the license to use excel anymore, as didn’t want to pay the steep annual charge, when a product like officelibre is so good and free to use. Any other thoughts or advice you have, would be awesome. Cheers