Incase anyone else is having this problem, I've found a solution, which was because I had not upgraded to Windows 8.1 due to a graphical error when I tried to update it last time, so by updating it to 8.1 it has fixed my audio and video problems.
Hi, I bought an Inspiron 15 3521 from dell outlet in august and it has been perfect, however recently I keep having trouble with its audio and video. After about an hour of my laptop being on, the audio no longer works and videos will load but will not play. I've tried updating the audio driver and it says it is already updated, and plugging in earphones into the audio port also does not produce sound. However, plugging in a USB headset does allow sound again, but unplugging it will still cause no sound to come out from the speakers. I'm pretty certain this isn't a hardware issue with the inbuilt speakers since restarting the PC will cause the audio and video to work properly again. While clicking on the volume slider, no sound appears to be playing from the computer itself, which confuses me. Any help would be great, thanks :)
Inspiron 15 3521 Audio and playing videos do not work after being on for an hour