لو سمحتو المساعده

Assuming that you are using CheckedListBox control, use this code to check all the checked boxes

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer
        For i = 0 To CheckedListBox1.Items.Count - 1
            CheckedListBox1.SetItemChecked(i, True)    'set the value to False if you want to uncheck the checkboxes
        Next
    End Sub

...Hope that helps