To turn on ToggleKeys
ToggleKeys is designed for people who have vision impairment or cognitive disabilities. When ToggleKeys is turned on, your computer will provide sound cues when the locking keys (CAPS LOCK, NUM LOCK, or SCROLL LOCK) are pressed. A high sound plays when the keys are switched on and a low sound plays when they are switched off.
Open Accessibility Options
On the Keyboard tab, under ToggleKeys, select the Use ToggleKeys check box.
To turn off ToggleKeys, clear the Use ToggleKeys check box.
To open Accessibility Options, click Start, click Control Panel, and then click Accessibility Options.
To use the keyboard shortcut which allows you to turn ToggleKeys on and off by pressing the NUM LOCK key for five seconds, on the Keyboard tab, under ToggleKeys, click Settings.
If the Use shortcut check box in the Settings for ToggleKeys dialog box is selected, you can turn ToggleKeys on or off by holding down the NUM LOCK key for five seconds.