I want to delete all info off of my ipod and sync it with new music/info

my ipod video 5th gen. has all old music and info on it. the computer i originally had used when i set it up is not working, i dont know the original user name and password. I need to know how to set it up as though it were a brand new ipod on a brand new computer. also make sure the serial number is registered to me still.