If you don't remmeber the passcode, then you have to restore your iPod to factory settings. Put your iPod to DFU (Device Firmware Upgrade) Mode and restore it from iTunes. Follow the steps below;
Note : Put it to DFU Mode while connected to computer and also in DFU Mode your iPod will remain blank. Let me know if that didn't worked..Only click Accept after we solved the problem. Best Regards, Ashik
iTunes application is that something I have to download?