Normally, I'd figure the driver is currently incompatible with the latest 8.1 Update (and contact MS, Dell (Alienware) and the audio chip maker TS about it). . . but you seem to indicate audio was working after the update and then failed sometime later.
I hope it is a driver issue and LatiosXT's up to date Windows certified driver works. I do note that the specs for the laptop (assuming it is a Alienware M14x R2
) indicate not a Realtek but a Creative Soundcard chip
[Creative Sound Blaster Recon3Di High-Definition 5.1 Audio with THX TruStudio Pro Software].
Of course it could be that the audio has failed; which is likely since the laptop's speakers are not recognized assuming you have actually been installing the correct driver. I assume headphones do not work either? Did you check audio driver settings or the app's manager for setup configuration?
Still under warranty? If not, you can buy an inexpensive USB sound device
. Of course it will be headphone or line out only.