If you are not using a very weird WordPress setup this should be the file that controls all the dynamic subfolders (permalinks, categories, archives etc.).

If you are lucky clicking the “Update Permalinks Structure >” button under “Options -> Permalinks” may be enough to rewrite the .htaccess file.

Otherwise you could manually check how it looks. In my WordPress installation the category part of it looks like this:

RewriteRule ^category/(.+)/feed/(feed|rdf|rss|rss2|atom)/?$ /index.php?category_name=$1&feed=$2 [QSA,L]
RewriteRule ^category/(.+)/(feed|rdf|rss|rss2|atom)/?$ /index.php?category_name=$1&feed=$2 [QSA,L]
RewriteRule ^category/(.+)/page/?([0-9]{1,})/?$ /index.php?category_name=$1&paged=$2 [QSA,L]
RewriteRule ^category/(.+)/?$ /index.php?category_name=$1 [QSA,L]


I see that the ones that don’t work all have spaces in the names. For example, the link to the Usabilty category is http://www.webword.com/category/Usability News/

Did you recently change the category names?