use NumericUpDown tool with time in c#

You are "buying water by the river:" Win Forms makes what you want here very easy:

1. put a DateTimePicker on your Form: 'TimePicker24

Set these Properties of the DateTimePicker:

Format: Custom
CustomFormat: HH: mm: ss tt
ShowTextBox: False
ShowUpDown: True
Checked: False

2. put a TextBox on your Form: 'TimeTextBox

3. create a ValueChanged EventHandler for the DateTimePicker:

private void TimePicker24_ValueChanged(object sender, EventArgs e)
{
    TimeTextBox.Text = TimePicker24.Text;
}

You now have a fully functional 24-hour style time picker. Of course, you can set-up its initial properties as you wish.

I suggest you keep the current time value selected in the DateTimePicker ... as a DateTime value ... in a variable for further use:

private DateTime CurrentTime;

private void TimePicker24_ValueChanged(object sender, EventArgs e)
{
    CurrentTime = TimePicker24.Value;
    TimeTextBox.Text = TimePicker24.Text;
}