There seems to be an influx of customers who have forgotten the passcode on their iPod touch, iPhone, or iPad. Although this is an unfortunate frustration, the fix is relatively easy, and (hopefully) painless, provided you have your music/apps/other data backed up on your computer.
(I need to warn you, this fix will erase all data on the device itself. As long as everything is backed up on your computer, you have nothing to worry about.)
Basically, you need to restore your iPod/iPhone/iPad in “recovery mode”. In order to get your device into Recovery Mode, you first need to turn off your device(hold the Sleep/Wake button until the “slide to power off” prompt can bee seen, slide it!). Now, that your device is off, make sure your usb dock connector cable is plugged into a usb port on your computer, but NOT plugged into the device. iTunes should be open during this process. While holding down the Home button, plug your usb cable into the device, keep holding the home button until you see the “Connect to iTunes” screen (iTunes logo+usb cable).
You should now get an alert in iTunes that states a device in “recovery mode” has been detected. Click OK, and you are now able to restore the device, erasing the user added data, as well as the passcode.