|If you're not seeing an IP when you do an ipconfig command then something is definitely wrong.|
I would start by rebooting and then checking to see if you have a valid IP. If you do, it was likely just a brain fart on the PC's part. But I would keep an eye on it in case it does it again which would indicate problems with the NIC.
If a reboot doesn't do the trick. I would first check for more recent drivers for the NIC. If there are newer ones apply them and check. If that doesn't fix the issue, the next thing I would try is resetting the TCP/IP stack. To reset your TCP/IP stack first o pen a command prompt window (ie: Start >> Run >> type cmd and hit Enter) and perform the following command:
netsh int ip reset c:\resetlog.txt
Note If you do not want to specify a directory path for the log file, use the following command:
netsh int ip reset resetlog.txt
Then reboot the computer.
If that doesn't fix the issue I would try removing the NIC from Device Manager and then reboot and let windows "find" and reinstall the NIC.
If none of the above fixes the issue, I'd buy a new NIC and install it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.