The usual "NEED MORE INFO" plea.. We aren't telepathic here, and can't read your brain to find out what you didn't tell us!
I'm guessing you have a a bad "mini-stereo" patchcord, a bad R-chan amp, or a bad soundcard (in that order).
Which model of Creative speakers?
Is it a "subwoof" setup?
Did you take the WHOLE setup (including subwoofer and cables) over to your friend's house for the test?
Most Creative (and other mfrs as well) have the amps in the subwoof. The "right speaker" by itself may have some controls, but there's no "power' in said speaker. The weight alone should tell you that.
Non "subwoof" speaker systems usually have both R and L amps in one speaker box, the heavy one.
The fastest way to eliminate the soundcard and it's jack is to plug in a known-good pair of earbuds or headphones into the pooter's green jack directly. (Even "dollar tree" earbuds are OK for this, if you know they work). The volume might be exceedingly low (especially if the green jack is configured for 'line out"), but you should hear both channels evenly.
As an aside though (and hoping you checked that), there IS a "fader" control in the Windows Volume Control under either "Advanced Settings" or "Mixer" depending on Windose version and/or sound device setup. It could also be in the application that came with your sound hardware.
Sometimes there are conflicts, which one you are using AT THAT TIME can get confusing if that happens. (Early RealTek HD Win7 apps did this, they updated those "rather fast")