suppose the user is opening the course page to see course info i want to chck that if the user is login then user can access page else it goes to loginpage through " Response.Redirect("Login.aspx");" first login then revert to the page from where it goes to login page by using this
Response.Redirect(Request.Cookies["path"].Value.ToString());

but it is not working it is giving the error that
Object reference not set to an instance of an object.

Question

suppose the user is opening the course page to see course info i want to chck that if the user is login then user can access page else it goes to loginpage through " Response.Redirect("Login.aspx");" first login then revert to the page from where it goes to login page by using this
Response.Redirect(Request.Cookies["path"].Value.ToString());

but it is not working it is giving the error that 
Object reference not set to an instance of an object.

anonymous · Answer

I don't know ASP but I know what your issue is.
You need to instantiate the object before you can use it. I'm guessing it's the response
Response r = new Response(); (use response properly of course)