The following macro should attach the normal template to the current document without updating styles.
Code:
Sub AttachNormalNoStyles()
'
' Attach Normal Template without updating Styles
' written by Charles Kenyon 2015-09-27
' https://www.msofficeforums.com/word/28024-word-2007-template-missing-share.html
'
With ActiveDocument
.UpdateStylesOnOpen = False
.AttachedTemplate = Application.NormalTemplate.FullName
End With
End Sub
For information on what to do with a macro see
Installing Macros.