CSCGAL answered a post of mine and php help

This thread grew out of @msimonds applying @Dani’s vBulletin mod_rewrite tutorial. The notes below are a compact, practical checklist and a tiny reproducible test that focus on the environmental issues that most often make rewrite rules appear to do nothing (rather than on rule syntax itself).

• Confirm the server actually has mod_rewrite enabled. With shell access run apachectl -M or httpd -M; otherwise ask the host.
• Verify .htaccess is being read. A simple functional rewrite test (see below) will show whether the file is processed. If .htaccess is ignored, check AllowOverride in the Apache vhost config.
• Put rules in the forum root (the directory that contains index.php) and avoid rewriting vBulletin admin/install or attachment scripts. Exclude paths like admincp and install from broad catch-all rules.
• Clear vBulletin caches and make sure any Admin CP URL settings match the rewritten targets.
• Use logging to diagnose rule application: older Apache used RewriteLog/RewriteLogLevel; newer releases use LogLevel with rewrite tracing. Hosts may need to enable this.

A minimal end-to-end test (place this .htaccess in the forum root and create a test.php that echoes a short message):

# .htaccess (forum root)
RewriteEngine On
RewriteRule ^rewrite-test$ /test.php [L]

<?php
echo 'rewrite OK';
?>

If this test returns the expected string at http://domain/rewrite-test then the server is processing rewrites and the remaining work is rule logic and exclusions. Back up the original .htaccess before changes and run all changes on a development copy whenever possible. This expands on the setup and troubleshooting points raised by @Dani and reflects the situation described by @msimonds.