Computer & itunes wont recognize i-touch

went to apple store recently & had tech restore my 8GB i-pod touch restore (completely froze up and I couldnt get it to restore?). Now when I plug it into my computer (my computer and I-tunes) doesnt recognize that its even plugged in. Cant be the usb cable or the port because when I plug in my kids i-touches they work fine. I can still use it through wi-fi for the internet etc but no music or files on it? HELP!!!!