Why don't you change this line:
DialogResult result = TopMostMessageBox.Show("Your Password will Expire in" +
" " + Futdays + " " + "Day(s)" + "\n" +
"Do you want Change it now?",
to real like this:
DialogResult result = TopMostMessageBox.Show(string.Format("Your Password will Expire in {0} Day(s).\nDo you want Change it now?", Futdays),
It's much more efficient...