Is this is an iPod Touch?
You have to restore your iPod from iTunes on your computer. You can restore it by putting it to DFU (Device Firmware Upgrade) Mode. DFU Mode is a mode which will allow you to restore your iPod to working condition. Put your iPod to DFU (Device Firmware Upgrade) Mode and restore it from iTunes. Follow the steps below to put your iPod to DFU Mode;
Note : Put it to DFU Mode while connected to computer and also in DFU Mode your iPod will remain blank.