Answer:
Without me everyone would lose their head. What am I?
What force and strength cannot get through I with my unique teeth can do.
I am a protector of the scoreboard.
Flat as a leaf round as a ring. I have two eyes but can't see a thing.
I go from house to house a messenger small and tight. Whether it rains or snows I sleep outside at night.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.