Columbus on but no sound through speakers.

Started off a couple of weeks ago where I would open car and start and headunit would come on but no sound even though volume was up halfway. Would turn engine off and lock doors then unlock and start again and then it would come on. Sometimes it would take a few attempts. Now it's been over a week and nothing. Comes on fine everything works apart from no sound. Even though when parking the beeps still are there. Reset to factory settings but still no joy.