What is the best over the counter medication to treat: sore itchy throat with a voice that’s gone, painful cough with yellow/green phlem and blocked nose with congestion?

URI symptoms . Need more information but try warm drinks, cool mist humidifier and nasal saline drops but if symptoms persist over ten days or more get examination .
Voice rest. and humidification of air are best treatments for laryngitis. It will take up to 2 weeks for your voice to return. Avoid excessive coughing, but sometimes it is better to expectorate sputum rather than having it stay inside.
Depends. Usually warm saline gargle, local anesthetic lozenges (Cepacol etc) and at times zinc lozenges may be helpful. In the case of a viral infection, the symptoms should start to improve after a few days and subside in less than 10, If you have a bacterial infection such as sinusitis, antibiotic may be needed.