USB external audio

[h12]

[Moderator note: This post, and only this post, was originally attached to the 3 year old thread If sound doesn't work - Things to check [Mar 26, 2010], and had no title. -Hu]

i use usb exernal audio ,when i change to it from mixer its not having sound . What can i do ?? even its being recoginsed by the system

what else software can iuse in order to configure the sound options .for example pulse audio etc .