Windows – sound is turned off. How to turn sound back on

Try MonitorES. You can find more information about this little app on Lifehacker:

Tiny, portable utility MonitorES not only turns off the monitor when you lock your PC, it also pauses almost any media player and even sets your Google and Yahoo IM status to away. We've written about this utility before, but since then it has updated with support for nearly any media player, added support for Yahoo Messenger, and you can now use it to simply pause your media with the Pause key. As before, you simply need to launch the utility, set the options, and the next time you lock your workstation your monitor will turn off, and your media will pause.

1. Open Notepad or any text editor you use.
2. Copy the following single line to the text: (new ActiveXObject("Shell.Application")).ShutdownWindows();
3. Save as "Shutdown.js" (without the quotes) anywhere you like on your computer.
4. Create a new shortcut that points to Shutdown.js.