Follow the proceedure below to get a visual indication of all modules used on your page:-
From the backend of your admin, go to Extensions->Template Manager. Click on Options (usually in the top right corner) and set 'Preview Module Positions' to enabled, then load up the website page you want to see the active module positions for, in your web browser.
In your browser, look at the URL field of your browser. Inspect the URL in the URL Address Bar, you need to see if there are any "parameters" at the end of the URL. If so, these will be separated from the main part of the URL by a question mark. For example, in the URL http://ujoomla.com/index.php?id=23, the "id=23" is a parameter.
If there are no parameters at the end of the URL, just add "?tp=1" to the end of the URL and press RETURN. For example, http://ujoomla.com/index.php?tp=1.
If there are already parameters in the URL, add "&tp=1" to the end of the URL and press RETURN. For example, http://ujoomla.com/index.php?id=23&tp=1.
The page will reload and the module positions will be outlined in red.
The limitation with this is that you can only see those modules that have been published.