I found a solution for the mute and CCMenuItemToggle questions.
You can just use setEffectVolume(0) and setBackgroundMusicVolume(0) as Walzer Wang mentioned.
When you want to let the sound back, just use setEffectVolume(1) and setBackgroundMusicVolume(1).
As for CCMenuItemToggle question, you can use the setSelectedIndex(I didn’t see this method on Doxygen, but you can trace the code , and you will find it) to make CCMenuItemToggle to show which image for you.
For example, if user choose sound off when he leave the game last time, and when he comes back, the sound control need to use the sound off image and make sound/music off.
Something like musicButton->setSelectedIndex(1).
Hope it will help other newbies like me.