Unfortunately when people have problems and try to resolve them on their own
then they cause more damage than the initial problem warranted. In your case,you
have broken sound and perhaps video.

In the worst case you may need to re-install Ubuntu, but this can be done
without loss of data. In the best case you can get the proper drivers and
settings and continue without problems. Just be patient and do not do too much
without guidance and you may reduce the severity.

Tackle each problem separately. Ubuntu knows your hardware since it detected it
and set it up in the first place. It is just a question of finding what is
interfering and setting things up properly. Fix one then the other. Video is
more important. Get it back then work on the sound.

I don't know your card so I can't give specific advice. Post what is relevant
and someone can help.