Currently Being ModeratedNov 24, 2012 8:52 AM (in response to johnozed)
The iPod is only playing out of one channel (hence one earbud)? I assume you have tried another set of headphones to make sure that your current set is not damaged or faulty?
You can also work through the remaining five 5 R's of troubleshooting to rule out the possibility of a software error/glitch.
It might also be a good idea to let the iPod's battery fully drain. Then charge it back up and restore it once more in iTunes.
Otherwise, it's likely a hardware issue with the iPod's headphone jack, meaning you'll need to take or send your iPod in for service either via Apple or a third party repair service. Here is Apple's repair pricing.
Note that they don't actually repair the device, but exchange it for one of the same generation, model, and capacity. A third party service will actually replace the damaged part for a little less. Google "iPod headphone jack repair" and you should get a number of results to work with.