My cord connects to an outlet but not to my computer

My cord for my Ipod charges when I plug it into an outlet which means that it works. But when I plug it into the computer, it does nothing. No charging sign appears, no box pops up on my screen. Nothing.

Any suggestions?

I tried to clean out all the lint or dust that could have collected, i switched the way the charger head (or whatever it is called), and all the ports I put it into.

I updated my Ipod. Turned everything off, then on, then off again.

Help?