Dude, check out my question and the solutions people offered... I'm pretty sure i had the same problem as you, so give the solutions a go  https://community.dell.com/thread/24132-need-help-fixing-unresponding-windows-audio-for-alienware-17-r4

As killerdk12345‌ says (what worked for them) was to:

1. First, do a ePSA Diagnostic Test. If it passes the main test on the first page, continue to Step-2.

2. On the second page of ePSA, test the audio card and speakers. If it passes, continue to Step-3

3. If you want, you can try an easy " Windows-10 Repair Install"

https://www.tenforums.com/tutorials/16397-repair-install-windows-10-place-upgrade.html

If it works, you are done.

If it does not work, or if you are looking for a more comprehensive and thorough attempt at trying to repair the software on your computer (like before moving to replacing hardware) you can continue to Step-4

4. Do a full Nuke-and-Pave (clean Windows Install followed by appropriate drivers). You will also have to re-install all your programs.

https://community.dell.com/thread/24064-alienware-15-r2-fps-super-low-somedays-and-computer-runs-slow-somedays-help

If bios didn't fix it you may want to look into an external usb audio interface used for home recording....you can run a set of pc speakers off of it or a set of headphones. They're pretty cheap for a small one, even cheaper used at a pawn shop or try used gear at guitar center.