Rooster not extending neck
Is it wry neck? I don't have any experience but here's a thread with pictures and treatment. http://www.backyardchickens.com/t/1037872/3-or-4-year-old-rooster-is-it-wry-neck
Isolate him until you figure out what is going on.
Sounds like it could be wry neck, which can be a deficiency of Vitamin E. Treating with Poly Vi-Sol, Vitamin E and selenium is the cure.
It also could be a form of Mareks, which obviously you don't want to mess with (but does not mean the end of your chicken world).
BYC has a good article on Mareks with also information on other diseases which can mimic Mareks. http://www.backyardchickens.com/a/the-great-big-giant-mareks-disease-faq
It is concerning that he doesn't want to eat but simply wants to sleep. That is never a good sign, along with the twisted neck.
Try the vitamin regiment first. It won't hurt. If it is a deficiency, you will generally see improvement within a day or two.
If it is Mareks, nothing can be done and the bird will slowly waste away.
Hopefully vitamins will do the trick.
Edited by Lady of McCamley - 11/6/15 at 12:36am
There can be degrees of wry neck as with anything, especially since it is a vitamin deficiency related problem.
Glad to hear he is eating and drinking. Pump the Vitamin E into him (with selenium) and see what happens in a few days.
Let us know how he is doing.