Get Latitude and Longitude using GeoLocation feature of browser and save to database in ASP.Net

Here I have created smaple that full-fill your requirement.

I hope this will help you out.

HTML

<div>
    <script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
    <script type="text/javascript">
        if (navigator.geolocation) {
            navigator.geolocation.getCurrentPosition(function (position) {
                var latitude = position.coords.latitude;
                var longitude = position.coords.longitude;
                document.getElementById("<%=hfLat.ClientID %>").value = latitude;
                document.getElementById("<%=hfLon.ClientID %>").value = longitude;
                var coords = new google.maps.LatLng(latitude, longitude);
                var mapOptions = {
                    zoom: 15,
                    center: coords,
                    mapTypeControl: true,
                    navigationControlOptions: {
                        style: google.maps.NavigationControlStyle.SMALL
                    },
                    mapTypeId: google.maps.MapTypeId.ROADMAP
                };
                map = new google.maps.Map(
            document.getElementById("mapContainer"), mapOptions
            );
                var marker = new google.maps.Marker({
                    position: coords,
                    map: map,
                    title: "Your current location!"
                });

            });
        } else {
            alert("Geolocation API is not supported in your browser.");
        }

        function GetAddress() {
            var lat = parseFloat(document.getElementById("<%=hfLat.ClientID %>").value);
            var lng = parseFloat(document.getElementById("<%=hfLon.ClientID %>").value);
            var latlng = new google.maps.LatLng(lat, lng);
            var geocoder = geocoder = new google.maps.Geocoder();
            geocoder.geocode({ 'latLng': latlng }, function (results, status) {
                if (status == google.maps.GeocoderStatus.OK) {
                    if (results[1]) {
                        document.getElementById("<%=hfAddress.ClientID %>").value = results[1].formatted_address;
                        Address = results[1].formatted_address;
                        localStorage.setItem("Address", Address);
                    }
                }
            });
        }

        function GetAddressDetails() {
            GetAddress();
            document.getElementById("<%=hfAddress.ClientID%>").value = localStorage.getItem("Address");
            localStorage.removeItem("Address");
        }
    </script>
    <style type="text/css">
        #mapContainer
        {
            height: 300px;
            width: 500px;
            border: 10px solid #eaeaea;
        }
    </style>
    <div id="mapContainer">
    </div>
    <asp:HiddenField ID="hfLat" runat="server" />
    <asp:HiddenField ID="hfLon" runat="server" />
    <asp:HiddenField ID="hfAddress" runat="server" />
    <asp:Button ID="btnSave" runat="server" Text="Save" OnClick="Save" OnClientClick="GetAddressDetails()" />
    <div>
        <table id="tblDetails" runat="server" border="0" cellpadding="0" cellspacing="0"
            visible="false">
            <tr>
                <td>
                    latitude :
                </td>
                <td>
                    <asp:Label ID="lblLatitude" runat="server" />
                </td>
            </tr>
            <tr>
                <td>
                    longitude :
                </td>
                <td>
                    <asp:Label ID="lblLongitude" runat="server" />
                </td>
            </tr>
            <tr>
                <td>
                    Address :
                </td>
                <td>
                    <asp:Label ID="lblAddress" runat="server" />
                </td>
            </tr>
        </table>
    </div>
</div>

C#

protected void Save(object sender, EventArgs e)
{
    this.tblDetails.Visible = true;
    this.lblLatitude.Text = hfLat.Value;
    this.lblLongitude.Text = hfLon.Value;
    this.lblAddress.Text = hfAddress.Value;
}

Screenshot