1. Check the "Optimize Windows Sound and Audio Configuration" option in the Optimization Master, which will cause no sound when turning on and off the machine. Try removing this check (if you have this software) .

2. Try the following method:

Start/run/enter regedit, open the registry editor, find the [HKEY_CURRENT_USER\Control Panel\Sound] branch, and change the subkey Beep Just change the key value from "No" to "yes".

3. Open Control Panel/Sounds, Languages ??and Audio Devices/Sounds and Audio Devices/Sounds/After selecting the "Windows Default" setting in the drop-down list of the sound scheme, press Apply to confirm.

4. If the fault persists, restore the system or reinstall it.

How to use the system restore that comes with the system:

The system restore that comes with the system: "Start"/"Programs"/"Accessories"/"System Tools"/"System Restore", click "Restore my computer to an earlier time", click Next, you will see a dark date on the date page, that is the restore point, after you select it, click Next to restore (Win7 restore System, in Control Panel then Devices and Security sub-option then Backup and Restore sub-option).

I have XP. If you also have XP, you can go to another computer and copy this key value to your computer.