Are you using a set of speakers or an internal speaker on a lap top or monitor Henry? First hover over the little speaker icon bottom left on the menu bar. You can click on that and turn up the volume to 100%. If you are using external speakers are the plugged in and switched on?
Hi Ivor I was waiting for Henry to come back after making sure the obvious had been checked. I was then going to post him the microsoft sound check diagnostic link that will check for drivers and compatibility issues. Henry does not say whether the sound was OK until say an upgrade was done. Nor do we know whether he has recently installed an app. like media player or suchlike.
Have a look at this "H". Read through fist and either click on the blue "try the audio troubleshooter" or follow the instructions that begin " select the Start button". The square being the windows key bottom left.
Some times as well "H" a shutdown and reboot sorts it if there has been for instance an Adobe upgrade done in the background without you being aware of it. If none of this works I will tell you how to do a system restore. Just do not panic or click on any sites offering a solution. They are a nuisance.
Not a good thing to do "H" once you have started system restore. You must have had the warning at the beginning. Never mind it is done now. A safe reboot may get you back in. Read through this and pick an option you are comfy with.