after insert the data to db i need to show a message and it will redirect to another page

This could be used for selecting random name from the table...this could not perfectly match of your desire...but try like this...
private void timer1_Tick(object sender, EventArgs e)
{
try
{
label1.Text = DateTime.Now.ToLongTimeString();
cn.Open();
SqlDataAdapter da = new SqlDataAdapter("select*from client", cn);
DataSet ds = new DataSet();
DataTable dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource = dt;
cn.Close();
if (textBox1.Text == null && textBox2.Text == null && richTextBox1.Text == null)
{
MessageBox.Show("no task allocated");
}
else
{
try
{
//here using cro algorithm
Random RandomNumber = new Random();

int rand;
int r = int.Parse(label5.Text.ToString());
rand = RandomNumber.Next(0, r);
string ip = listBox2.Items[rand].ToString();
//TcpClient socket = new TcpClient("192.168.1.56", 1095);

TcpClient socket = new TcpClient(ip, 1095);
NetworkStream nw = socket.GetStream();
cn.Open();
SqlCommand cd1 = new SqlCommand("update task1 set task='" + richTextBox1.Text + "',assigned=getdate(),deadline=getdate()+10 where ip='" + ip + "'", cn);
cd1.ExecuteNonQuery();
cn.Close();
}
catch (Exception ep)
{
// MessageBox.Show(ep.ToString();
}