After setting the default opening mode of Word, the icon changes, how to restore to the default style?

Delete registry (significant effect)

After opening cmd, enter regedit to open the registry, and then find the files in the following three places, delete them!

HKEY_CLASSES_ROOT.doc

KEY_CLASSES_ROOT\Word.Document.8

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts.doc

Or you can adjust the opening method.