Display icons for caps lock, sound (<Fn> + <F8>), Num lock etc.

Have unintentionally done something to my computer which means it no longer displays the momentary icons on screen when you select "Caps lock", or switch on the sound using keys <Fn> + <F8>, or press <Num lock key> etc. etc.  These functions still work but there is no momentary icon on screen to confirm you have just pressed these keys.  (This change happened far too long ago for me to use System Restore.)  Cannot find any help on how to change the settings for this / how to restore these momentary visual icons, so very grateful for any help on this.  Thanks

(Note: I selected "Writer" at random under the heading "Product" below, as there is no category that matches this enquiry in the drop-down menu offered.)