If this is not style-based numbering, try copying the format from a working paragraph and pasting it to the problem paragraphs. You can use Ctrl+Shift+C to copy and formatting and Ctrl+Shift+V to paste it.
For stable numbering, I recommend style-based numbering, though.
With style-based numbering, you can try resetting paragraph formatting, including numbering, by selecting the relevant paragraphs and pressing Ctrl+Q.
For more on properly setting up multilevel lists associated with paragraph styles, see
http://www.shaunakelly.com/word/numb...g20072010.html.