If such a disaster happened, first note that most probably the cause of it was not Windows or Office updates. Perhaps you use some Office addon or similar utility that interfered and changed your normal template. You should not also blame your PC manufacturer.

In any case, first try to protect your normal template by locating it in Windows Explorer and changing its properties to “read only”. Then make sure you keep backups of your templates and all your personal documents and settings.

Keep also a system image, with a program that is not able only to restore but also to mount a system image as a virtual drive, letting you browse it and select files to copy.

Of course you need to discover the cause of your problem. During the next Windows and Office updates keep Word closed and see if even this way your normal template is overwritten. Try also to remove temporarily addons or other programs that interfere with Word’s functionality.