If everything from the above fails for whatever reason the last resort you can do the following:
Open terminal
cd ~/Library/Keychains
ls
When you 'ls' here you will see a folder that contains a bunch of random number liks so:
94ED610F-DD96-4ECF-A2BC-7D2F8651A464 (this number is unique on each system)
rm -rf 94ED610F-DD96-4ECF-A2BC-7D2F8651A464
Reboot
<when you log back in everything should be back to normal>
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simple fix