Sounds like it was shot on a camcorder with a mono mic? You will be unable (correct me if I'm wrong) to create a true stereo soundstage using this method but at least it will give you audio on both channels rather than just one. Do you have access to Adobe Premiere Pro? If you do, then you need to click on the audio track in the timeline to highlight it, then in Audio Effects->Stereo->depending on which audio track is available to you, click on either Fill Left or Fill Right and drag and drop the effect onto your audio track on the timeline. Play the clip back and see if you are getting both left and right audio on the audio meter.

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