Thank you for writing to the Dell Community Forum.
May I know from when did the audio stop working? Did the audio stop working both on the headphones and speakers?
I recommend you to run the Diagnostics from the F12 menu and perform the audio test to see if the audio works fine. Please find the steps from the link below:
Also update the latest audio drivers from Dell Support site to see if the audio works fine. In case it doesn't work, try a system restore to a previous date when the audio worked fine.