Movie playback

I didn't do any movies before on D7000, but yesterday I gave it a shot. It looks great but I can't get sound to work. I haven't look into it deep yet, and hope someone can have quick solution. I'm playing back on Windows media player. Should I use something else?

I dont know if the D7000 has a mic port or wether you can turn the mike off. Check your menu to see if maybe you turned the mic off or have it set to mic port.