The iPod 5 that I bought from a classmate is iCloud locked. How can I activate this iPod?

i buy an ipod 5 to my classmate then later on the ipod got terminated and i dont know the original icloud account

The only person who can clear up this situation for you is the person whose iCloud account is linked to the device via the iCloud activation lock. I can only assume it is the classmate you purchased it from. If not, there's nothing you or anyone else can do.