WiFi Connection Problem in Windows 7/Windows 10 upgrade
If you can't connect to your router in Windows 7, try deleting the network and recreating it here:
Control Panel\Network and Internet\Manage Wireless Networks
I have a complicated network in my home that includes a battery of switches, five wireless routers and a couple of range extenders. I had to reconfigure the system because of interference from other routers in the local neighborhood. Everything was in place and tested with everything else (several PCs, half dozen notebook computers, and about a dozen other devices such as tablets, telephones, game systems, etc.)
Shortly after getting everything working, I began to do upgrades to Windows 10 to a few devices. The upgrade process was not a smooth one, but I got a couple of them working eventually. A third one simply would not upgrade to Win 10 no matter what I tried. It offered no clue as to why it failed and was happy to give it another go. I tried about a half dozen times over a period of three days before I gave up.
Whatever happened during the abortive attempts to upgrade to Windows 10, the notebook in question stopped being able to connect to one of the routers. I tried everything I could think of including swapping out the particular router in question. The notebook could connect to one named WiFi router that was further away, but could not connect with another even though it was closer and more powerful. I eventually thought that it must be an incompatible router. However, when I swapped in a new router, it could not connect to that one either.
The only difference between the router it could connect to and the one it could not connect to was the WiFi network name (SID).
I taught networking and have done this sort of thing for decades. I am not perfect, but I can set up a WiFi network okay and I can do the usual troubleshooting.
In desperation, I ended up deleting the wireless network and recreating it. That miraculously did the trick. It would appear that somehow the network information had become corrupted.
Anyway, there is hope for at least this one issue.