You have probz hidden it!
have a look through your computer
Most likely a hidden app, or just restore it.
Either go to settings, and check if the app store app is hidden, if not, then restore your iPod.
If you still face any problems, go to Apple and try to find a way there =p.
If it's not jailbroken it try jb it. Then respring. The appstore is there with the firmware, it may just be missing it's icon.
Restore your iPhone and it should be available. If not contact apple.
Please take a screenshot I can't believe you .Never hapenned to me.
You can try to restore your ipod.
Restore.
Also, this happened to me... Infact the only app I had was music stocks and wether. Restore.
Do you have a custom firmware on your device? That could be the problem. Please try to restore it with a official firmware.
Make sure you don't have it in a folder that you've over looked. Another possibility is that it was blocked in parental controls. In that case, simply reset your Apple device in iTunes.