how to go control back to StartUp Form

you can send your object of form1 to form2 and add a constructor with a parameter object of form2 like this :

In form1 when you are calling form2 :

Form2 frm2 = new Form2(this);

In form2 you can create a constructor like this :

public static Form1 Frm1 = new Form1();

public Form2(Form1 form)
{
     Frm1 = form
}

now you can access any control of form1 after setting its modifier to public.

Hi Ravi ,
first you must create an overloaded constructor in form2 and a global object of form1 , your already existing default constructor is :

public Form2()
{
     InitializeComponent();
}

The global object and the overloaded constructor code will be :

public static Form1 Frm1 = new Form1();

public Form2(Form1 form)
{
     InitializeComponent();
     Frm1 = form;
}

Now you can set your datagridview in form1 's modifier to public .

Then in the click add button event you will insert this code for opening form2 :

Form2 Frm2 =new Form2(this);
Frm2.show();

now in the form2 code you can update your datagridview in form1 using :

Frm1.dataGridView1.Rows[...].Cells[...].Value = "<your desired="" data="">";
</your>

I Hope this time it is clear ,
Good luck
:)