focus

Thankyou for replying.
Actually, I created a user control which consists of panel and inside a panel I have buttons. I gave added this user control as a reference to windows application. In form I added this usercontrol and one textbox of form. I gave button press event in user control and appropriate function of diplaying the text in textbox in form. My problem is at runtime, When I press a button on the keyboard, the action is not entering to the usercontrol code and when I click using mouse on the button i.e by giving the focus to the button only the execution is entering into the usercontrol code. Please, give me the solution..

I don't understand what you mean by "giving the focus to all the buttons".

If i understand what you're trying to do, you should simply handle the click event of the buttons.
Create a public method in your form with a string as parameters.
And call that method in the click event handler.

FORM
---
public void ChangeTextboxText(String str)
{
      this.textbox.Text = str;
}

USERCONTROL
---
foreach (Control ctrl in this.Controls)
{
     if (ctrl.getType() == new Button().getType())
       {
                ((Button)ctrl).Click += +=new EventHandler(button_Click);
        }
}

        void button_Click(object sender, EventArgs e)
        {
            ((Form)this.Parent).ChangeTextboxText(((Button)sender).Text);
        }