We can find address components Country, State, Postal code etc. from latitude and longitude using google map api.
For this google provide a service. We have to call this service using post method. Service return result in two formats xml or json based on the parameter passed as xml or json.

using System.Xml;
public void GetAddressFromLatLon(Decimal Latitude, Decimal Longitude)
{
    string result = null;
    System.Net.WebClient webClient = new System.Net.WebClient();
    var apiUrl = "https://maps.googleapis.com/maps/api/geocode/xml?latlng=" + Latitude + "," + Longitude + "&sensor=false";
    var searchRequest = "";
    webClient.Headers.Add("content-type", "application/x-www-form-urlencoded");
    result = webClient.UploadString(apiUrl, searchRequest);
    XmlDocument xbook = new XmlDocument();
    xbook.LoadXml(result);
    string CountryCode = string.Empty;
    string CountryName = string.Empty;
    string StateCode = string.Empty;
    string stateName = string.Empty;
    foreach (XmlNode node in xbook.DocumentElement.ChildNodes)
    {
        if (node.Name == "result")
        {
            foreach (XmlNode node1 in node)
            {
                if (node1.Name == "address_component")
                {
                    foreach (XmlNode node2 in node1)
                    {
                        if (node2.Name == "type" && node2.InnerText == "country")
                        {
                            foreach (XmlNode node3 in node1)
                            {
                                if (node3.Name == "long_name")
                                {
                                    CountryName = node3.InnerText;
                                }
                                else if (node3.Name == "short_name")
                                {
                                    CountryCode = node3.InnerText;
                                }
                            }
                        }
                        if (node2.Name == "type" && node2.InnerText == "administrative_area_level_1")
                        {
                            foreach (XmlNode node3 in node1)
                            {
                                if (node3.Name == "long_name")
                                {
                                    stateName = node3.InnerText;
                                }
                                else if (node3.Name == "short_name")
                                {
                                    StateCode = node3.InnerText;
                                }
                            }
                        }
                    }
                }
            }
            break;
        }
    }
}

Call the service by passing Latitude and Longitude.

Decimal Latitude = Convert.ToDecimal(50.95846878);
Decimal Longitude = Convert.ToDecimal(6.97181002);
GetAddressFromLatLon(Latitude, Longitude);