all music i brought from iTunes didnt download to my new ipod

i got the new ipod 5th gen touch when i signed in to my itunes account it downloaded some songs but not all of it. be fore my new ipod i had the 2nd ipod touch. i brought some music total of 21 songs a video and an app. now i only have 11 of those songs and no app and video. how can i get all my songs? i dont wanna buy them again. i cant even find my music in my purchese history