If your 'Side Switch' (right upper side above volume buttons) is defaulted to 'mute' the sound, then if may have inadvertently been moved to that position - there are some other possibilities but see if that is your problem for starters.
I have finally rectified the problem, it did it itself!, I plugged it into the computer and got into iTunes . . . I had done this a few times prior to when the problem started but now it works!!! Great! Thanks all for your support
Have restored it a couple of times but did it again yesterday and now it works! This is great, still do not know why it happened, but hoping all is OK now as we are off on a trip for approx 6 Weeks but in a lot of areas there will be no coverage, but we can cope with that. Thanks again for your help!