7559 F3 key not working

I have had this laptop for 2 years now and have has little to no problems with it. This morning the F3 key (mainly used to turn the volume up) stopped working completely. Is there anything I can look into or run on the laptop to get an answer as to why as it has done this or do I just have a broken key that I have to get replaced? It does not appear damaged and worked perfectly until it stopped altogether.