mudassarkhan her's my code ===>

HTML:

<div>

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList_SelectedIndexChanged" Height="17px" Width="249px">
</asp:DropDownList>
<br />
<br />
Name<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
<br />
Surname<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<br />
<br />
Username<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<br />
<br />
Password<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
<br />
<br />
Role<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
<br />
<br />
<asp:Button ID="Button1" runat="server" Text="Update" />
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:Button ID="Button2" runat="server" Text="delete" />
</div>

Behind code :

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DropDownList1.Items.Add(new ListItem("--Select--", ""));
DropDownList1.AppendDataBoundItems = true;
String strConnString = ConfigurationManager
.ConnectionStrings["parallelConnectionString"].ConnectionString;
String strQuery = "select name, surname from tblusers";
MySqlConnection con = new MySqlConnection(strConnString);
MySqlCommand cmd = new MySqlCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = strQuery;
cmd.Connection = con;
try
{
con.Open();
DropDownList1.DataSource = cmd.ExecuteReader();
DropDownList1.DataTextField = "name";
DropDownList1.DataValueField = "surname";
DropDownList1.DataBind();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
con.Dispose();
}
}
}

protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
String strConnString = ConfigurationManager
.ConnectionStrings["parallelConnectionString"].ConnectionString;
string strQuery = "select name, surname, username, password, role from tblusers where name = @name";
MySqlConnection con = new MySqlConnection(strConnString);
MySqlCommand cmd = new MySqlCommand();
cmd.Parameters.AddWithValue("@name", DropDownList1.SelectedItem.Text);
cmd.CommandType = CommandType.Text;
cmd.CommandText = strQuery;
cmd.Connection = con;

try
{
con.Open();
MySqlDataReader sdr = cmd.ExecuteReader();
if (sdr.HasRows) {
while (sdr.Read())
{
TextBox1.Text = sdr[0].ToString();
TextBox2.Text = sdr[1].ToString();
TextBox3.Text = sdr[2].ToString();
TextBox4.Text = sdr[3].ToString();
TextBox5.Text = sdr[4].ToString();
}
}
else
{
TextBox1.Text = "not found";
}

}
finally
{
con.Close();
con.Dispose();
}

}

i added two buttons UPDATE and DELETE and hopefuly work .