Minecraft sound glitch

The problem I am having is that the sound on Minecraft is only working
Sometimes. This affects both title screen and all game modes. This is nothing to do with my PC as I have played music at the same time to tell if it was to do with my PC. My PC is running 64-bit windows 7.

I logged in successfully and I expected sound on the title screen when I pushed single or multiplayer.

*What actually happened was there was no sound even though my speakers were turned on and up and the games sound was on 100%.

Steps to Reproduce:
1. I do not know how to reproduce this bug as it just happened one day. I have found a temporary fix that lasts until I close Minecraft. The temporary fix is F3 and s at the same time this workes in game but it would make minecraft a lot better if it had sound automatically when it started. Is there a permenant fix for this glitch?