Thanks for replying back, you were offline when I responded earlier.
Possibly the built-in speaker or microphone has a problem.
Does it make any beeps or sounds at all, perhaps when it is turned on? If it does, then the speaker is ok.
What happens when you play back on a computer? Is there no audio then either? If so, then the microphone is suspect - it may just be that the small microphone is blocked up with some debris, and needs clearing out.
Reply back and let me know what you find....
Ok Sue, then that confirms it is likely the speaker if there are no sounds at all.
Go to Menu - Sound Settings and ensure the button and shutter sounds are turned ON there.
If they are, but you cannot hear them, then the speaker is defective.