It will be better and quick if I can access your computer remotely to fix the problem ..
for that please follow the below steps
Please open the below link URL in browser
and then click on I agree button .
After that click on Download link to download a file and run it
that is an issue with your sound
can you hear other sounds on your computer ?
if you can than your skype is set to use the wrong speakers
click on the skype menu
then audio settings
click on the playback device and make sure that you have the right device selected.
if your computer does not have any sound on anything than let me know and i can show you how to fix that.
If you are using it on a phone or tablet rather than a computer let me know that as well please it would be different instructions