您没有指定使用哪种身份验证技术。

但仍然使用以下Code语句，您可以找到返回URL：

 Request.Params [  ReturnUrl] 

您可以编写一些代码，以便在超时发生时您可以使用上面的返回URL将用户重定向到返回URL页面

I am not seeing Returnurl in query string when I do click on log in I am modified loggedin event at login control. Is that the reason I am not able to maintain returnurl in the url when users go timeout? Please tell me how can I retrive returnURL in loggedin event? So that I can redirect the user to that page.

Please help its really very urgent.

You didn''t Specify which kind of Authentication technique are you using.
But still using the following Code statement you can find the Return Url:

Request.Params["ReturnUrl"]

You can just write some code so that when time out Occurs you can Redirect the User to the Return Url Page using the Above Return Url