Can someone explane me why am i banned for 4 days ?

it says ninja looting i never lead any dung or raid never even ninja something WTF is happening ?

If it's 4 days, it's dungeon not raid. You don't have to lead it to get banned. Someone could have reported you if you pressed need on an item that was not for your current spec.

oh that the neck i press need on 1 neck but i traded him after cos he said he need it and he reported me after ?

It's possible if it was not for the spec you were using. But someone else in the group also could have reported you. You won't get any more details about your ban. They don't show the proofs they have to protect the identity of the person who reported you. If you think the ban was unfair, you can make a ban appeal using support system on website here. But it's probably not worth it for a 4 day ban since ban appeal tickets are lowest priority and can take up to a week to be checked.