Last week I fixed a few by the following methods.
1. Went to Device Manager and went to the Network Adapters then expanded that tree. I then right clicked on the Eithernet then selected uninstall device. I did NOT uninstall/remove the driver files.
Repeat for WiFi.
Now use Action, Scan for changes an re-test. May need to reboot.
2. On another PC I had to forget the old networks. Old would also mean these networks that you can't connect to. How to forget WiFi connections is on the web.
3. And a failed internal WiFi card. Had to pull out an USB WiFI stick and that fixed that machine.
I have a ZTE Blade v7. I used to access the Internet on it in shops regularly until about two weeks ago when the Internet suddenly stopped working in all shops. For the Internet to work again, I have to get about 100 feet away from the shop. Please can someone tell me how to get it working in shops again?