The clicking sound, is caused by the hardisk read/write arm trying to find boot sector.
either because the battery power is low or the hard has crashed.
So charge it 1st by connecting to a PC, although you may not see it in iTunes or the desktop.
What do you see on the iPod screen when you connect it to a PC or Mac?
if you are lucky, after resetting (Press Menu and Center button for 10 secs)
connect it to PC and format it.
But if the red X and clicking sound is still there, you can't format it, it is a goner, and last hope is to