No sound after OS change.?

Today i changed my operating system from windows xp service pack 2 to windows xp windows 7 viena.

Now i dont get any sound from either my external speakers or my headphones.

Before doing the change i backedup my entire c drive.



How can i fix this please help.No sound after OS change.?
Go to device manager and make sure the sound driver has been install ed, if not you will have to search the web for it.No sound after OS change.?
you can try downloading the drivers for your computer and install those. it might work.No sound after OS change.?
Call Microsoft or go on there support page. Gd luck