Permalink Issue – Can't Remove /index.php/ without 404 errors

Hi, I’m quite new to wordpress, i’ve recently updated to 3.4.2 (manually) and can’t seem to get my permalinks working again (https://www.markseabridge.com). Its a pretty simple site and i just want the top nav items to direct to the relevant page (ie https://www.markseabridge.com/about/) but can only now get the default settings to work (https://www.markseabridge.com/?p=123) or the post name with index.php/in the extensions (https://www.markseabridge.com/index.php/sample-post/).

Although I backed everything up via my FTP (and database from PHPMyAdmin) I foolishly didn’t have show hidden files selected so my .htaccess file wasn’t backed up.

I’ve created a new .htaccess file following what I’ve read on the forums (code pasted below). When i update to the same custom structure that previously worked (simply /%postname%/) I get no error message just “Permalink structure updated.” However it hasn’t updated, instead i get 404 errors.

Can anyone help shed any light? I’ve tried deactivating all the plugins, switched to the twentyeleven theme and still the same errors.

Thanks in advance from a frustrated designer trying to get to grips with WP.

<—- code for my .htaccess file —->

“# 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”