itunes and windows 7 don't recognize ipods or itouch

I have followed the article about similar problem, several times, to no avail. I have 2 ipods and an itouch. No problem until all of sudden 2 days ago neither iTunes or Windows 7 will recognize the devices. Have spent 2 days trying to sort out. Uninstalled and re-installed iTunes. Verified the latest driver for apple mobile device support. Have restarted computer and all devices (numerous times). Have verified Windows 7 updated. Have switch out usb cords. No luck on anything. Am totally frustrated. Any other ideas? Thanks