Hi Frank, welcome to WinDrivers.
We really do need some more information to be able to help you. If you don't know the full details of what model of card is in the system, I suggest downloading the free
Everest program. Let us know what the program reports of your sound setup and your system configuration when you run it.
Alternatively if you do know exactly which card it is, let us know, along with what happened at the time your sound ceased working eg is it a new installation of Windows, or a new sound card, etc.