No sound in metro/modern apps

I've got a very strange issue which I can't see anywhere else on this site. Basically sound works perfectly fine in the desktop and all legacy apps however there is no sound at all in any metro apps. Skype/ IE 10/ Xbox music/ games all have no sound.

My sound in all apps (modern and legacy) has been working fine up until 2 days ago. I've checked any recent updates and I don't see any in the last few days that could have changed this. I haven't installed any drivers or changed any setting in the last few days either. I really don't understand how this could have happened.

I've noticed that when playing a song in Xbox music, it comes up along the bottom bar as playing but when pressing the volume buttons, it does not show the artist and play/skip controls like it used to. Also, interestingly, modern Skype will not connect to my webcam and neither will the modern camera app. This started happening at the same time as the sound stopped working, so I'm pretty sure they're connected in some way. It's as if the modern part of the UI is not able to connect to my speakers and my webcam. Webcam works fine in desktop Skype.

I've tried restarting my laptop but that hasn't helped.

I'm running Windows 8 pro on a Dell Inspiron 1564 which I upgraded from Windows 7 in December.

Any help on this would be really appreciated.