Hello Old-Man-wants-iPod-back,
Thank you for using Apple Support Communities. Sounds like your PC isn't recognizing your iPod nano anymore. We also notice that you're already coming from the following resource here: If your computer doesn't recognize your iPhone or iPad - Apple Support
This resource does have great steps to help isolate and troubleshoot this issue. If your issue continues, we could still recommend some more steps. Follow the steps below:
1.) If you're using security software on you PC, you might want to disable it. These types of softwares can sometimes cause interference with your devices when using iTunes: Resolve issues between iCloud for Windows or iTunes and third-party security software - Apple Support
2.) Check for new drives that you might have to manually install for your iPod: Update drivers manually in Windows - Microsoft Support
3.) Restart the Apple Mobile Device Service (AMDS) on Windows - Apple Support
We hope these steps help you. Thank you for using Apple Support Communities. Take care.