Good point - Hayles66. Check the system sound mute button - either the slide switch next to the volume control or possibly, depending on the version of iOS you have, this could be on the far left of the multi task bar - accessed by double-tapping the Home button and then 'flicking' the screen to the right.
Its not muted or anything,.i have sound in ipod and youtube,.but i dont have sounds almost all the gmes installed here,including keyboard clicks and notifications,..