If the issue persists, continue with the next steps. The initial instructions help to correct keys that are saved in the registry key in the HKEY_CLASSES_ROOT folder. However, in some cases, this is not sufficient. It may happen that Office keys have been created in the HKEY_CURRENT_USER folder. They are always incorrect and must be removed.
Open the Windows Registry: From the Start menu, type regedit.exe in the search box, and then press Enter
Open the HKEY_CURRENT_USER folder and search for all the possible Office extensions: .xls, .xlsx, .xlsm, .xlsv, .doc, .docx, etc.
All the folders named as an Office extension must be deleted.