404 error after changing permalinks wordpress

Question

My site is a Wordpress-site created with PHP.

I have made changes in permalink default to postname. It works fine in Chrome and Firefox but not in IE8. The front page displays correctly but when I click a link to another page, it shows a 404 page not found error.

I'm using Wordpress version 3+.

.htaccess file is

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

where WordPress is folder name. also in apache rewrite_module is enable

Answer 1

First put a .htaccess file in your /var/www/ folder and make it writable. Second, suppose your wordpress blog is in /var/www/blog folder then go to /etc/apache2/sites-available/ and make following changes in default file

<Directory /var/www/>
    Options +ExecCGI 
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All
            Order allow,deny
            allow from all
</Directory>
<Directory /var/www/blog/>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All
            Order allow,deny
            allow from all
</Directory>

Now restart apache to make sure changes have taken effect. Hope it helps.

Answer 2

After trying all of these answers and the instructions on codex.wordpress.org, I needed to enable mod_rewrite on Apache: https://stackoverflow.com/a/5758551/728287