Well, you could change your windows settings so that Stereo Sound channels all come from your Right speaker.
Start > Run > "SNDVOL32"
That will bring up the Audio shifters, for your main sound (should be something like "Play Control" or "Main", slide the Right-Left Balancer until you hear everything and not nothing.
It's possible that this sort of thing happened and is the reason why you can only hear out of one of the speakers.
In WinAmp... you can go to the Equalizer (Hit ALT+G or the "Config" arrow on the main window) and there is a Right-Left slider there.