Question

How to make as by pressing to the close button, make so that the form was not closed, and it was turned off?

private void Form1_Closed(object sender, EventArgs e)
{
    Form1.Hide();
}

So the form is all the same closed.

Answer 1

You should do it on FormClosing not FormClosed event like this:

private void Form1_FormClosing(object sender, EventArgs e) {
    Form1.Hide();
    e.Cancel = true;
}

FormClosed means the form is already closed.