Posture. Neck pain is often caused by poor posture or ergonomics, and may respond to physical therapy for strengthening, stretching and postural correction. You're benefit from seeing a rehabilitation medicine doctor, they can determine if the cause is more serious like a disc or joint problem, and even do an injection which can help relieve pain for the right individual.
Sore Muscles. Our heads are heavy! Its our neck muscles' job to support it &they can get sore from holding your head in a position all day. Ex. Studying, working over head, sleeping in an odd position. Osteopathic doctors (D.O.) can do treatments to help realign your neck (& rest of your body) & muscles. You may be holding your neck in a certain position to compensate for a misalignment elsewhere. See your dr.
Multiple causes. From musle spasm to cervical disc problem to viral infection, there are too many causes to enumerate and give definitive answer.
Depends. Neck pain can come from trauma such as a car accident to no known cause. If the pain is localized to the neck with no numbness or tingling into the shoulders, arms or fingers then more then likely it is a muscle strain or inflammation. It usually responds to anti-inflammatory meds and heat/ice. Arm weakness or numbness see your doctor.
Can anyone advise me on what physio therapy exercise I should do to get rid of shoulder ache and neck aches?
CONSULT FIRST. Consult with your doctor to make sure that you need therapy. There are many pathologies that may cause aches, pain or muscle spasm.
See an expert. The physical therapists will be more helpful than me in this regard.