Soundsystem never plays sounds because of missing file

Sounds never play in Minecraft 1.7 & 1.8!

What I expected to happen was...:
I expected it to play sounds when I play Minecraft 1.8.7.

What actually happened was...:
It never played sounds when I clicked anything!

Steps to Reproduce:
1. Try to play a world and press certain buttons at the same time.
2. If it never works, restart your PC.
3. It it never works, download a new version.