Go to device manager and see if those speakers exist on that PC. Most likely it does not. Reboot, making sure that your interface or rig is is turned on and connected so as the PC comes up it finds it. If that doesn't work, re install what ever driver for the codec was installed in the first place.
Bottom line you didn't give enough information for us to be more specific.
Second bottom line: Windows sucks, but it is what we have.