How The Checkboxes Remains Checked After I Click On The Save Button

protected void Page_Load(object sender, EventArgs e)
{

try
{

if (!Page.IsPostBack)
{
BindGrid();
}
}
catch (Exception ex)
{
}

//



}

protected void Button2_Click(object sender, EventArgs e)
{


DropDownList1.Items.Remove(DropDownList1.SelectedItem);
con.Open();
string query = "Delete from Role2 Where Role_Name <> 'Administrator' ";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();
con.Close();

}




protected void Button1_Click1(object sender, EventArgs e)
{
string fruit = TextBox1.Text.Trim();
if (!string.IsNullOrEmpty(fruit))
{
DropDownList1.Items.Add(new ListItem(fruit, fruit));

}


string role = TextBox1.Text;
con.Open();
string str = "insert into [Role2] (Role_Name) values(@Role_Name)";
using (SqlCommand insertuser = new SqlCommand(str, con))
try
{
insertuser.Parameters.AddWithValue("@Role_Name", TextBox1.Text);

insertuser.ExecuteNonQuery();

}
catch (Exception ex)
{
}
con.Close();


}
private void BindGrid()
{
string qry = "select distinct * from Role1";
DataSet ds = dut.GetDataSet(qry);
GridView1.DataSource = ds;
GridView1.DataBind();

}


protected void Button3_Click(object sender, EventArgs e)
{

//for (int i = 0; i < GridView1.Rows.Count; i++)
//{
// CheckBox chk = (CheckBox)GridView1.Rows[i].Cells[2].FindControl("CheckBox1");
// if (chk != null)
// {
foreach (GridViewRow row in GridView1.Rows)
{
if (row.RowType == DataControlRowType.DataRow)
{
CheckBox chkRow = (row.Cells[2].FindControl("CheckBox1") as CheckBox);
if (chkRow.Checked)
{



string strID = row.Cells[0].Text;
string Pages = row.Cells[1].Text;
string status = "Y";


con.Open();
string query = "Update Role1 set [Add] ='" + status + "' where ID= '" + strID + "' and Pages= '" + Pages + "'";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

BindGrid();
con.Close();
}


else
{

string strID = row.Cells[0].Text;
string Pages = row.Cells[1].Text;
string status = "N";



//cmd = new SqlCommand("insert into Role1(Checkin_Add) values(" + status + " where ID= '" + strID + "' and Role_Name='" + strName + "')", con);
string query = "Update Role1 set [Add] ='" + status + "' where ID= '" + strID + "' and Pages= '" + Pages + "'";
SqlCommand cmd = new SqlCommand(query, con);
con.Open();
cmd.ExecuteNonQuery();

BindGrid();
con.Close();
}

}

}

}

}
This is my whole code please check.