For Each c As Control In fraSeite2.Controls
 
                    If TypeOf c Is TextBox Then
                        c.Text = String.Empty
                    End If
 
                    If TypeOf c Is GroupBox Then
 
                        For Each c2 As Control In c.Controls
                            If TypeOf c2 Is TextBox Then
                                c2.Text = String.Empty
                            End If
 
                            If TypeOf c2 Is GroupBox Then
 
                                For Each c3 As Control In c2.Controls
                                    If TypeOf c3 Is TextBox Then
                                        c3.Text = String.Empty
                                    End If
                                Next
 
                            End If
 
                        Next
 
                    End If
 
                Next

If TypeOf c Is CheckBox Then
 
                 c.checked = false
 
End If