My Ipod won't connect but it used to--what is wrong?

I can connect my camera to my computer and download pics but I can't connect my Ipod anymore. When I plug Ipod into my computer, it doesn't show it is connected & I can't of course sync the songs on there. I can charge the battery through my computer, though. The cord for my Ipod works. Any advice? I'm computer illiterate at times, so please let me know what I can do. My Pod is one of the newer ones. Thanks.