I’m not a sophisticated user. The program was updating as my computer was booting up. I’ll admit that I clicked on an error box without fully understanding what the error was. Now when I attempt to open one of my documents,
Windows is asking me to download an app from the Microsoft store to open. Possibly, I need to do that, but wouldn’t know which one to pick.
If you have just updated LibreOffice, the error box was probably saying that you need to reboot before you can use it. Click Start menu > Power > Restart (NOT Power Off - default for that is just hibernate).
After you have restarted Windows, can you click Start menu > LibreOffice x.x > LibreOffice Writer, and does Writer open? If so, can you click File > Recent documents > [a recent file] and open that document?
If that works, can you open a document by double-clicking it in File Explorer?