First plug the speakers into something else if you can to make sure they both work.
Second, go in the start menu, click control panel, and then click "sounds and audio devices". Go through all the volume and advanced options you can find in here and see if you can find a "balance" option and center it.
Third, if you have another program that controls the audio output on your computer that you installed or came installed on your computer, make sure that program has the balance centered. I do not know exactly how to find out if you have one of these programs on your computer, somebody else may be able to help with that.
Fourth, check to see if whatever program you are using to play the audio (windows media player, VLC, itunes) has a balace option and center it. The easiest way to rule this out would be just to try a different program and if that one does the same, then it is most likely not a setting in the program.
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