Terrible stiff/sore neck. no idea why, don't remember doing anything to it. really irritating...cannot get in comfortable position. help?

Multiple causes.: It can be caused by sleeping in an awkward position, straining ones neck to look to one side or the other for a prolonged period, working at a desk with ones head bent. Or it could be due to an arthritic cervical spine problem such as a vertebral degenerative change or disc disease. Less common would be a vertebral fracture. Use ice, then heat, ibuprofen. Get it examined.