Wrong way round Geeky. A mono track will play the same in both speakers.
Rewind, sounds like you have a stereo track, but with no data in one channel. When you open it, you should see that one channel has a soundwave and the other is just a straight line.
You need to convert it to mono, selecting only the channel that has data as the source. This may or may not sound OK, depending on whether the channel with data was from a mono track or just from one side of a stereo track.
Make a copy first if you're not sure, or stick it on mediafire and I'll have a look at it for you.