System alway restarts silently with speaker volume reset to zero.
Hi,
Follow the steps provided below and check if it helps:
How to Adjust the Windows Startup Sound Volume
a) Click the "Speaker" icon in your system tray. This icon is located next to the computer clock.
b) Use your computer mouse to drag the volume bar down. If the bar is at the top, the volume of the Windows startup sound is at the maximum; at the bottom, the sound is off. Adjust the bar to your preferred volume.
c) Restart your computer. When the computer boots up you will hear the Windows Startup sound based on the volume level you set.
Reference:
Adjust the sound level on your computer
http://windows.microsoft.com/en-US/windows7/Adjust-the-sound-level-on-your-computer
Hope this helps