how can I fix my dragon age inquisition sound?

This can happen for several reasons. The most common, I think, is when the game tries to use the wrong audio device, in which case it might help to just unplug the audio devices you're not using. For instance, a PS4 controller is detected as an external audio device because it has an audio jack and Windows has a bad habit of switching to the PS4 controller when you plug that in.

It might help if you shared a dxdiag file. It might give a clue of what's happening.

https://help.ea.com/en/help/pc/how-to-gather-dxdiag-information/