Answer:
A type of hammer that brings a room to order.
What hangs others yet can unintentionally hang itself?
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
I can be cracked, I can be made. I can be told, I can be played.
In the night a mountain, in the morning a meadow.
People take me on walks and I run and have fun. What am I?