Throat itch disturbs sleep. Lozenges doesn't help at all. Keeps coughing the whole day.?

GERD. There are many causes of chronic cough. Laryngopharyngeal reflux is a common cause, as is chronic rhinitis and asthma. It would be a good to see an otolaryngologist to evaluate your larynx, as this will often lead to the correct treatment. There is also neurogenic cough which is treatable. You shouldn't have to live with your cough.
Post-nasal drip... One possibility for this is post-nasal drip that may require nasal sprays to control so your cough can resolve. Other possibilities include gerd and bronchospasm. Since they all require different treatments, you should see your doctor for precise diagnosis so proper treatment can be initiated.