Answer:
I lose my head in the morning and regain back it at night.
I move without wings Between silken string I leave as you find My substance behind.
Against the sun I protect your eyes and am often worn on the face of spies
I am whole but incomplete. I have no eyes yet I see. You can see and see right through me. My largest part is one fourth of what I once was.
You throw me out when you use me and take me in when you are done.
Long and slinky like a trout, never sings till it's guts come out.