Internet not working: some troubleshooting tips

Connecting to internet sometime becomes so frustrating that you curse your laptop. Sometimes I have spend hours to connect to internet specially when I switch between multiple wifi networks.
Here are some common troubleshooting tips when connecting to wifi network.

Before starting, first check if every thing is on, you know, your wifi router in on, WLAN is activated, wifi adapter of your laptop is enabled. If everything is fine, try to Switch off modem and all internet devices for at least one minute and then switch on.  Then roll up your sleeves and try following options:

A. FIRST THING TO DO: Auto repair
first go automatic, simply right click on the network icon at right bottom of you screen (near the clock) and select "Diagnose and Repair" or you may have something similar like "Troubleshoot". This will take care of most of the problems.
You can also find this option from Control Panel > Network and Sharing Center.



After this open Network and Sharing Center and it still shows cross in your network map. click on that cross, it will also repair.

B. NOT CONNECTING TO WIFI NETWORK
1. check name of the network, if it is same as an old network you were connected to, there would be a conflict. E.g.: If you have your home network named DLink and the new network also has same name, it wont connect until you delete old network setting. Better keep different names for different networks. Make it personalised but dont make it too personal as it is being broadcast. ALWAYS PUT A PASSWORD (WPA key) on your wifi network.
 Go to Network > Network & Sharing Center > Manage Wireless Network
delete old network OR update WPA password for same name

C. wifi Network not in the list of available network
1. check your router, there is button which enable/disable WLAN
2. if you know how to configure router setting, check WLAN settings
3. enable/disable wife adapter of your laptop

D. connected to network but INTERNET NOT WORKING
This should be taken care by option A of "Diagnose and Repair".
After that try these
1. open command prompt ("cmd" in run menu) in admin mode (Run As Administrator)
try these ipconfig commands
type "ipconfig /help" to know what this command does.  To reset ip address try these. first command will show current ip settings
1. ipconfig
2. ipconfig /all
3. ipconfig /release
4. ipconfig /renew

DNS not working. Can't open even www.google.com even when internet connection seems fine. This is my recent discovery , when net is well connected but cant resolve DNS
try  this
1. ipconfig /flushdns
2. ipconfig /registerdns

you can try playing with services, restarting DHCP, DNS, Network connection services etc. This may help sometime.

(some good options here for DNS error etc
https://www.wiknix.com/how-to-fix-err_connection_refused-in-chrome/
use these commands
ipconfig /release
ipconfig /all
ipconfig /flushdns
ipconfig /renew

netsh int ip set dns
netsh winsock reset
then restart computer
)

E. Net is connected but browser giving SECURITY CERTIFICATE ERROR
1. check the date and time setting. this is most common problem in older system that are unable to sync the clock properly.
Click on clock (right bottom of your screen) , Set the correct date and time by changing date and time setting.
Go to Internet Time > Change settings > update time

F. Sharing internet from mobile phone
USB internet is as costly as mobile data. So better use your mobiles "hot-spot", "internet tethering" or "internet sharing" options and use it as a wifi router. just play around "settings" in your mobile and you will find some option to share you mobile's data connection. Dont forget to put a password for your network.

This should help. Still try google for the specific problem you have using other device which is still connected to internet. You will find some help. Its not rocket science after all. :)