how do i connect to iTunes it used to work now it does not

When happens when you connect iPod to your computer running iTunes? Are you saying it does not appear in iTunes at all?

Watch iPod's screen when you connect it to computer's USB port? Does it say "Connected" or "Do not disconnect" or give other indication of a data connection? Or does it just show battery charging symbol? Or does it not react at all to being connected?

Is your computer running iTunes a Mac or Windows PC? If Windows, which release?