heyy umm you could try deleting your account then recovering it? or try redownloading them on a different account if you have one make sure you have more space than needed
If you downloaded them on your profile that your are using then it's either the disk not reading them, ( Black-Ops discs have been know to be crappy.) or Like he said you just need to clear your cache and re-download them.
There is DRM on it. You must download it from the market place sorry. USB method only works with DRM free content.
But Im In Kurdistan We Dont Have Bank Cards To Add Money In Internet Can You Help Me With Another Way