You didn't accidentally uninstall your NIC driver, did you? It's been a while since I went through troubleshooting network issues, so maybe I'm forgetting a simple step or two, but this is the direction I would go if my wi-fi stopped working.
It could be a few things that are hopefully easily correctable.
1) If you're on a laptop, some have a button that turns your wifi on/off. Make sure that it wasn't accidentally turned off. Also, on the task bar, by the clock, hopefully there's an icon indicating that you're not connected to the network. You can click on that to see if you can locate your network and then reconnect to it. If by some chance these don't fix your issue.....try restarting your computer again for good measures.
2) Make sure the NIC is detected under your network/settings. If you're on Windows 7 or later, just bring up the start menu and type in the following:
ncpa.cpl
Then press Enter. It should bring up your Network Connections window. You should see your network adapter listed there. Hopefully it shows up and there and it doesn't say "Disabled" on it. If it does, you simply need to RIGHT click on the icon and Choose ENABLE from the drop down menu.
3) If nothing is detected in the Network Connections window for step 1, you should take a look in the Device Manager - same as above, open the start menu and type in:
device manager
Then press Enter. In the Device Manager window, you should see an option called "Network adapters". There should be a drop down arrow on the left side of it, click on that arrow to show the network adapters on your computer. You could have more than one, depending on your computer. If you have any there and they have a yellow ! it could mean the adapter is disabled or perhaps a driver issue. If the adapter is disabled, right click on it and choose ENABLE.
If by some chance there is nothing showing up under Network adapters, perhaps you may need to try and find the network driver for your computer and install it. If this is a laptop, you may have to download the driver to a USB stick, copy it to your laptop and install it.
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