Display GridView Cell Value in TextBox on Cell Click using jQuery in ASP.Net

Here I have created sample that will help you out.

HTML

<div>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <script type="text/javascript">
        $(function () {
            $("[id*=GridView1] td").bind("click", function () {
                $('[id*=txt1]').val($(this).html());
            });
            return false;
        });
    </script>
    <asp:GridView ID="GridView1" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
        runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:BoundField DataField="FirstName" HeaderText="FirstName" ItemStyle-Width="150" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" ItemStyle-Width="150" />
        </Columns>
    </asp:GridView>
    <br />
    <br />
    Selected Cell Value :
    <asp:TextBox ID="txt1" runat="server" />
</div>

Code

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] { new DataColumn("FirstName"), new DataColumn("Name"), new DataColumn("LastName") });
        dt.Rows.Add("Pulodov", "Rustam", " Abdulloevich");
        dt.Rows.Add("Safarov", "Sarabek", "Rustamovich");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

Screenshot