Script working as Keypress, Event in asp.net stop

Question

how to use Keypress,KeyUp,KeyDown Event in asp.net

in last time i get a solution from here site for keypress events as script but now is stop

<script>

function getdata(e) {

if (e.keyCode == 13) {

SqlCommand cmd = new SqlCommand("Select * from TBL_PRD WHERE Barcode=@Barcode", Conn);

cmd.Parameters.Add(new SqlParameter("@BARCODE", TextBox3.Text));

Conn.Open();

SqlDataReader reader = cmd.ExecuteReader();

while (reader.Read())

{

TextBox3.Text = reader.GetString(1);

TextBox4.Text = reader.GetString(2);

DropDownList3.Text = reader.GetString(3);

//DropDownList2.Text = reader.GetString(4);

}

reader.Close();

Conn.Close();

//TextBox1.Text = "";

//TextBox2.Text = "";

}

e.preventDefault();

return false;

}

else if (e.keyCode == 9) {

SqlCommand cmd = new SqlCommand("Select * from TBL_PRD WHERE Barcode=@Barcode", Conn);

cmd.Parameters.Add(new SqlParameter("@BARCODE", TextBox3.Text));

Conn.Open();

SqlDataReader reader = cmd.ExecuteReader();

while (reader.Read())

{

TextBox3.Text = reader.GetString(1);

TextBox4.Text = reader.GetString(2);

DropDownList3.Text = reader.GetString(3);

//DropDownList2.Text = reader.GetString(4);

}

reader.Close();

Conn.Close();

//TextBox1.Text = "";

//TextBox2.Text = "";

}

e.preventDefault();

return false;

}

}

</script>

what is solution >>> ?

please help me