iTunes or the 3u tool helps to remove the Passcode disabled/iPhone unavailable. If you have no idea then you have to see the process. Remember all data was gone and you may have to insert your apple id if find my iPhone is enabled. You have some chance from fully disabled to enter the passcode option this [link|https://youtu.be/tMQQ8dy2bU0|process|new_window=true] that I follow helps me.