If I click on the documents icon to access my LibreOffice files, they are unreadable.,

I have Windows 10. I can access the LibreOffice files only if I click on the LibreOffice icon. If I click on the Windows documents icon on the start-up screen, the opened files are garbled.
When I try to back up files on to a memory stick, for example, they are also unreadable. This is very worrying. Can you help with a solution please?