A little exploration on the Internet revealed that the solution to the problem was easy enough. All Dad had to do was restore the system to a previous time. But because Dad's operating system was in Chinese, it wasn't going to be so easy to do a system restore.
But thank God for Google Translate! Dad used the facility to find the simplified Chinese characters for system restore. Cutting and pasting the characters into the the search box on the Start Menu of Windows 7, he was able to get to the system restore menu. This menu was in Chinese, but Dad did have a screenshot of the English menu, and so was able to fix the problem!