See, there's 2 ways to have the music screen controls. To get the time for the music, shuffle and repeat buttons, you have to tap the screen. When you tap it again, those disappear and all you see is the volume control at the bottom.
Oh, another thing: if you have lyrics of any songs in the song info on iTunes (you have to type it in or copy and paste on the computer), the lyrics will also show up when you have those controls on.
Try switching your iPod off for a few minutes, then switch it back on to see if its back. If it is still not working, then you can take it to either an Apple Store or an electronic technician to have it fixed.