USB Keyboard changed keymap automatically My USB External keyboard layout changed to this format.

And I am unable to reset it back to normal one (US input). Any suggestions on how to reset  it back?


Rebooted the system. No effect.
Reset PRAM. No effect. 
I don't have an additional keyboard to try. But I can try it in a while.
Either you're holding it down, or your Option key is stuck ;-)

Regular...

 

With Opt held - note the greyed key, marked in red

 

Also note this is a UK keyboard, but the main layout is the same UK/US