keyboard shortcut

[Harold Hoffman]

have an extra key 'Fn' (found at bottom to left of window key), in the past
have simultaneously used this key 'Fn' and either F3, F4, or F5 to either
mute, increase sound, or brighten the screen .......but somehow I have
turned off this ability and wish to know how to turn it back on
HARRY

 

[paulmd]

have an extra key 'Fn' (found at bottom to left of window key), in the past
have simultaneously used this key 'Fn' and either F3, F4, or F5 to either
mute, increase sound, or brighten the screen .......but somehow I have
turned off this ability and wish to know how to turn it back on
HARRY

Is this a laptop? and if so, which model?

If it's not a laptop, you have a keyboard driver issue, or something
realated to programming of the special features.