Q: The battery on my ipod nano 4th gen will not charge. How can it be changed?

Yes.  As to how you are to do that, you have a few options.

1. Send it to Apple and have them swap out the battery for a flat fee. See this page for more details.

http://support.apple.com/kb/index?page=servicefaq&geo=United_States&product=ipod

2. Send into a third party service center who can do the same battery swap job for a little less.  Google for possibilities.

3.  Purchase a replacement battery from an online dealer and swap it out yourself using the instructions over at http://www.ifixit.com/.

B-rock