I have an Asus B150-M-A mobo with an integrated graphics chip and
Realtek ALC887 codec. I connect it via HDMI cable to my living room TV
when I want to use the pc. It's worked very well for my needs (web
surfing and anime videos). Today, the audio stopped working. The
videos works.

At first I was thinking buy a cheap sound card because the current
problem is no sound, but I ran across a comment while googling that
indicated the problem will actually involve the on-board graphics chip
because that's the chip that combines the audio and video signals to
the TV via HDMI. Is this correct?

When everything is doee, I just want to get back to the way things were
before - use the pc to surf and watch stuff and display it using the TV
as my monitor like I've been doing. Obviously, buying a new mobo might
solve my problem, but would buying a video card or a sound card fix my
problem?

Thanks,

John