No Sound Playback

I tried everything i could. I don't know if this problem is from my PC or what but there is literally no sound when i press play or even input notes when editing scores. I'm on windows 8.1. I found the issue and i don't know what to do. there should be a drop-down list when i click on it but no matter how many times i click, still nothing. It doesn't even allow me to choose instrument sounds. please help. i need help badly. thanks!

GIT commit: f51dc11