Arduino Uno R3 not recognized by Device Manager

[gangnum3]

I purchased an Arduino Uno R3 this past July and have reached a dead end with troubleshooting. The bottleneck is that the device manager doesn’t recognize the Uno in com ports or other devices, nor with “Add New Hardware” option. I’ve followed the setup instructions to a tee, tried 3 computers (XP and Win7), several USB cables, and any info. on Adafruit and other forums. Any suggestions? – Thanks

[adafruit_support_bill]

Did this Uno ever work?
Does it show up in "unknown devices"?
Is there any sound from your computer when you plug it in?
Is there any LED activity on the Uno when you plug it in?

[gangnum3]

Yes, the device worked OK for a few days; initially to get it to work, I had to "Add New Hardware (XP)to get it recognized in dev. mgr., then it was simply not recognized by dev. mgr., and now it no longer shows up when using "Add New Hardware" option. It does get power (green light on), but no sound when plugged in and no listing in "other devices."

[adafruit_support_bill]

It sounds like the 16U2 chip has stopped working. When exactly did you purchase this Uno?

[gangnum3]

Wed, Jul 10, 2013 at 2:29 PM Jul 10
Order Confirmation No: 308817

[adafruit_support_bill]

That is outside of our usual repalcement policy. But if you contact [email protected] we can offer you a discount on a replacement.

Or you can try to re-flash the 16U2 as described here: http://forums.adafruit.com/viewtopic.ph ... 9&p=214947
Many people have been able to resurrect uncommunicative Uno's that way.

[gangnum3]

Bill-The problem didn't get solved, but it did get resolved. Thanks for you time and input.