I cant put songs on my 30gb ipod

Yeah, i cannot agree with you more, try to use an iTunes alternative.
iTunes alternative to manage or transfer iPhone iPod iPad music

Couple of things you might want to try to break down the problem.

- Change USB cable
- Connect your iPod directly to your computer and not through a USB hub
- Connect to another computer with iTunes installed. Is it recognized by iTunes.

You could also try using an iTunes alternative. If it works with an alternative, you might want to unsinstall and reinstall iTunes (backup your music first).

A list of iTunes alternatives is available here:

http://ipodmanagers.blogspot.com/

or here:

http://en.wikipedia.org/wiki/Comparison_of_iPod_managers

Try plugging it out and resseting it by pressing menu and the middle button for 10 seconds or something like that the plug it back in to see if itunes detects it