Uno Not recognized by Vista

My Uno was working Ok on my Vista PC. Now when I plug it in I get nothing. Not even the sound that a new piece of hardware has been pluged in. I have checked my USB cable, it is OK. I have tried deleting the Arduino software and starting all over again, no joy. The power light and L light on the Uno work as expected. Have I damaged the Uno, and made it obsolete? The com 3 that used to show up in Device manager, is no longer there. Any advice?

Do you have something that can work as an ISP? A second Arduino? A dedicated programmer?

Unfortunately I do not have another Arduino. You ask if I have an ISP. I am not sure what you mean by that? I did try to connect the Uno to my old laptop which uses Windows XP. I only plugged it in with a USB cord I did not download the Arduino software. I expected that if it was working the computer would at least find the new hardware and ask about a driver. It did not even find the hardware. The same as my vista computer.

PeterJ44:
I am not sure what you mean by that?

Then you don't have one.

I did try to connect the Uno to my old laptop which uses Windows XP. I only plugged it in with a USB cord I did not download the Arduino software. I expected that if it was working the computer would at least find the new hardware and ask about a driver. It did not even find the hardware. The same as my vista computer.

I hate to say it but the evidence indicates that the board is damaged or that the USB interface chip has been erased. If you are interested, a forum member offers a free repair service...

Or, if you get a second board or an ISP, you could try reburning the firmware onto the interface chip.

Does the L LED blink when the board is first powered? Or when you click the RESET button?

Yes the "L" LED does blink as required both when I plug it in to the USB and when I press the re-set button. The power light is also On.

The evidence indicates that the USB interface chip has been erased. The good news is that, with the right tool, there is a very high probability that the board can be resurrected. The bad news is that it does not sound like you have the right tool.

You will need a second board or a dedicated programmer to reburn the Atmega8U2 firmware. Or, you can ask Drew to try to reburn the firmware. Or, you can ask the vendor for help. Or, this may work...