What Causes A Prolonged Loss Of Voice?

Hi I had flu 2 weeks ago and began recovering and then lost my voice. I am now almost fully recovered from the flu but have still had no improvement in the lost voice. I can bearly make a sound in the morning and it gets to a point in the day when I can speak but it is very hoarse. I have never experienced this prolonged voice loss before and am very concerned as it has now been 2 weeks with no improvement.