I need to access signed in username and pass, which are saved in session variable from Silverlight page.
I remember something of accessing session variables from Silverlight but cannot get the code
I cannot remember the name of the video, which shows how to interaction between aspx page and silverlight plugin.
You can use WCF service marked with attribute:
And in web.config
This service will be available in asp.net session. You can get data from session object in some service method.
Also, you can pass the data from session with initParameters of silverlight plugin.
And you can look at RIA authentication service