To confirm it not being recognized by iTunes, from the menu bar, under View, select Show Sidebar. With the sidebar visible, does the iPod appear in the sidebar, under DEVICES?
If it does not, I would try shutting down and disconnecting all USB devices, including hub. Start up the computer with only standard keyboard and mouse connected (if normally used). Do this to Reset the shuffle
Run iTunes. Connect shuffle to a direct USB port on computer.
What version of Windows do you use?