You don’t access your form1, from which you created form2. In form2 button1_Click you create new instance of Form1, which is not the same as initial. You may pass your form1 instance to form2 constructor like that:
// Code from Form 1
public partial class Form1 : Form
{
public void PassValue(string strValue)
{
label1.Text = strValue;
}
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 objForm2 = new Form2(this);
objForm2.Show();
}
}
// Code From Form 2
public partial class Form2 : Form
{
Form1 ownerForm = null;
public Form2(Form1 ownerForm)
{
InitializeComponent();
this.ownerForm = ownerForm;
}
private void button1_Click(object sender, EventArgs e)
{
this.ownerForm.PassValue(textBox1.Text);
this.Close();
}
}