No sound on music players, YouTube videos etc. Only get system sounds

Solution 1:

Firstly, as Saurav Kumar mentioned in this comment Open System Settings from dash and click Sound Then go to Hardware > Profile and test other profiles that match your audio connections. You should test while running some media player. If it will not work, then look at Ubuntu's page about sound problems: Sound Troubleshooting or better yet, the more recent help wiki page.