any permalink structure other than default causing 404

When I change the Permalink structure from the default to any of the other options, it causes 404 errors. The only page that will come up is the opening index page.

I checked the plugins and none of them are causing these errors.

I’ve searched in the codex and these forums and see that it is likely the htaccess file that needs to be altered. Currently, there is no htaccess in the wp root, nor is there one for the root folder in the latest version download zipfile.

I found the following coding at http://codex.wordpress.org/Permalinks#Where.27s_my_.htaccess_file.3F

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

But the 404 errors continue unless the default permalink structure is chosen.

Alas, I understand very little about htaccess coding. Also, I think (but am uncertain) if my sister’s wordpress is on an apache rather than a IIS (windows) server. Could some kind soul please spell out the extra coding that should go into the htaccess file for the wordpress root folder?

Thank you.

E Morris