If they used the ethernet to connect to the net and it has suddenly stopped working then you could try removing the card from the device manager and rebooting and seeing if windows will install the device properly
to get the driver you need to find out what kind of ethernet card you have so that you can download the driver from the manufacturers website. See if there are any markings on the card itself. If not try and download Aida32 from
here install that on the machine and see if can tell you what the card is.
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