How can i retrive session from asp.net using Jquery

One way to handle this would be to create a Web Method or similar within your current page so that you could access the updated value of the Session via an AJAX call :

[WebMethod]
public static string GetSessionValue(string key)
{
     return Session[key];
}

Then you could make a POST call via AJAX to request the specific key that you needed (or you could ignore any parameters and simply hard-code the key that you wanted to pull within the method itself) :

public static string GetSessionDisplayName()
{
     // Use the name of your Session key here to retrieve your info
     return Session["DisplayName"];
}

And then you could use the following jQuery code to pull it with a parameter :

$.ajax({
     type: "POST",
     url: "YourPage.aspx/GetSessionValue",
     data: '{ key: "your-session-key" }',
     contentType: "application/json; charset=utf-8",
     dataType: "json",
     success: function(data) {
           // data will hold your Session value, use it here
           alert(data);
     }
});

Or without one :

$.post('YourPage.aspx/GetSessionDisplayName',function(data){
    // data will hold your Session value, use it here
    alert(data);
});