Hi,
1. Add new constructor in Form2 and add parameter of Form1.
From1 frm1;
public Form2()
{}
public Form2(Form1 refOfForm1)
{
frm1 = refOfForm1;
}
2. Pass parameter of Form1 and show Form2 from Form1.
private void showform2_click(Object sender,EventArgs e)
{
Form2 f2 = new Form2(this);
f2.show();
}
3. Call any method of Form1 from Form2 using 'frm1' object.
private void enableBtnInForm1()
{
frm1.EnableBtn();
}