Save user selected Language in Cookies in MultiLingual Website ASP.Net

Hi Prasunjeet,

You need to change BasePage Code and Master Page.

BasePage

protected override void InitializeCulture()
{
    string language = "en-ca";
    if (HttpContext.Current.Request.Cookies["Language"] != null)
    {
        HttpCookie cookie = HttpContext.Current.Request.Cookies["Language"];
        if (cookie != null)
        {
            language = cookie.Value.Split('=')[1];
        }
    }

    //Check if PostBack is caused by Language DropDownList.
    if (Request.Form["__EVENTTARGET"] != null && Request.Form["__EVENTTARGET"].Contains("ddlLanguages"))
    {
        //Set the Language.
        language = Request.Form[Request.Form["__EVENTTARGET"]];
    }

    //Set the Culture.
    Thread.CurrentThread.CurrentCulture = new CultureInfo(language);
    Thread.CurrentThread.CurrentUICulture = new CultureInfo(language);
}

MasterPage

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        string language = "en-ca";
        if (HttpContext.Current.Request.Cookies["Language"] != null)
        {
            HttpCookie cookie = HttpContext.Current.Request.Cookies["Language"];
            if (cookie != null)
            {
                language = cookie.Value.Split('=')[1];
            }
        }
        this.ddlLanguages.Items.FindByValue(language).Selected = true;
    }
}

protected void ChangeLanguage(object sender, EventArgs e)
{
    HttpCookie languageCookie = new HttpCookie("Language");
    languageCookie.Values["LanguageCode"] = this.ddlLanguages.SelectedValue;
    languageCookie.Expires = DateTime.Now.AddDays(30);
    HttpContext.Current.Response.Cookies.Add(languageCookie);
    this.Response.Redirect(Request.Url.AbsoluteUri);
}

Note : your each page must inherit BasePage.

public partial class _Default : BasePage

I hope this will help you out.