my ipod classic stored library was deleted after updating in windows

Try the troubleshooting on this page : If you see error 1415, 1417, 1418, 1428, 1429, 1430, 1436, or 1439 when restoring or updating an iPod in iTunes - Apple …

If that works, then you have all of your music in that computer's iTunes library ? If you don't then add it from your backup of your downloads/library via Add > To Library, and you can then sync it back to your iPod

how do delete music off of a ipod classic

Try connecting it to your computer's iTunes, change your music sync selection, and re-sync