Data Did Not Save Plz Help Me

i have made a windows applicatioon and connect to a database
but when i enter the data and presss the button then it did not save the data in database so what should i do ,here i m writing the whole code and please help me and solve this problem
private void button1_Click(object sender, EventArgs e)
{


SqlConnection CON = new SqlConnection(@"Data Source=.SQLEXPRESS;AttachDbFilename=|DataDirectory|Database1.mdf;Integrated Security=True;User Instance=True");

CON.Open();

//cm = new SqlCommand("INSERT INTO Student(RegNumber, Name, FatherName) Values ('" + txt_Registration_Number.Text + "','" + txt_Name.Text + "','" + txt_Father_Name.Text + "')", CON);

SqlCommand cm = new SqlCommand();

cm = new SqlCommand("INSERT INTO Student(RegNumber, Name) values(1000, 'Hasan Nizamani')", CON);
cm.ExecuteNonQuery();
CON.Close();
}

sheraz