Hi nauna,

Check this example. Now please take its reference and correct your code.

HTML

Default

<asp:TextBox runat="server" ID="txtCity" />
<asp:Button Text="Send" runat="server" OnClick="Send" />

Landing Page

<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?key=API_Key"></script>
<script type="text/javascript">
    window.onload = function () {
        if (window.location.search == "" || (window.location.search.split('=')[1] == "")) {
            if (navigator.geolocation) {
                navigator.geolocation.getCurrentPosition(function (p) {
                    var LatLng = new google.maps.LatLng(p.coords.latitude, p.coords.longitude);
                    var mapOptions = {
                        center: LatLng,
                        zoom: 18,
                        mapTypeId: google.maps.MapTypeId.ROADMAP
                    };
                    var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
                    var marker = new google.maps.Marker({
                        position: LatLng,
                        map: map,
                        title: "<div style = 'height:60px;width:200px'><b>Your location:</b><br />Latitude: " + p.coords.latitude + "<br />Longitude: " + p.coords.longitude
                    });
                    google.maps.event.addListener(marker, "click", function (e) {
                        var infoWindow = new google.maps.InfoWindow();
                        infoWindow.setContent(marker.title);
                        infoWindow.open(map, marker);
                    });
                });
            } else {
                alert('Geo Location feature is not supported in this browser.');
            }
        }
    }
</script>
<div id="dvMap" style="width: 200px; height: 200px">
</div>

Code

Default

C#

protected void Send(object sender, EventArgs e)
{
    string city = txtCity.Text.Trim();
    Response.Redirect("Landing.aspx?city=" + city);
}

 VB.Net

Protected Sub Send(ByVal sender As Object, ByVal e As EventArgs)
    Dim city As String = txtCity.Text.Trim()
    Response.Redirect("Landing.aspx?city=" & city)
End Sub

Landing Page

C#

protected void Page_Load(object sender, EventArgs e)
{
    Response.Write(Request.QueryString["city"]);
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    Response.Write(Request.QueryString("city"))
End Sub

Screenshot