Sorry to hear that you're unable to use your iPod nano currently.
I found a section of an article that would apply to your issue:
I would first try steps 1 through 10 in there, and if that doesn't work the article also links to a few other articles that could be of assitance:
- My iPod won't turn on
- iPod troubleshooting basics and service
- My iPod isn't responding or won't wake from sleep