اینجوری حل میشه
int index = Int32.Parse(lblSecond.Text);
int minute = Int32.Parse(lblMinutes.Text);
int hour = Int32.Parse(lblHour.Text);
if (lblSecond.Text == "0" && lblMinutes.Text != "0")
{
minute--;
index = 60;
lblMinutes.Text = minute.ToString();
lblSecond.Text = index.ToString();
}
if (lblSecond.Text == "0" && lblMinutes.Text == "0" && lblHour.Text != "0")
{
hour--;
minute = 60;
index = 0;
lblMinutes.Text = minute.ToString();
lblSecond.Text = index.ToString();
lblHour.Text = hour.ToString();
}
if (lblSecond.Text != "0")
{
index--;
lblSecond.Text = index.ToString();
}