Looking at images of that product, it appears to be more than just a sound board - you have an external control panel with it too. If it is something simple and mechanical wrong (lose socket that can be soldered back into place, lose switch, dodgy power wire, ...) then you might be in luck and it can be repaired without too much expense.
If it is something smaller scale though, a fault on one of the surface mounted components on the card or in the controller, you are almost certainly out of luck - those PCBs are not designed with being repaired in mind and replacing one might cost as much the whole device (unless you can work out which half is not working, and find someone who has the other half not working!).
What are the symptoms of the failure? Does the sound card still register as present to the OS? If not then it is almost certainly something on the card itself that has gone wrong. Do any normal power indicators come on when you try to use it? Do you get any sound at all with the volume at full whack? (if you get some sound, even just noise, when you up the volume that might imply that the amplifier, if that external box has one, is powered and trying to do something).