Diacritical Marks

[mrsg]

I can't access my full English language keyboard fully. Diacritical marks
appear when I use the keys at the keyboard perimeter. (example-question mark
appears as É)

 

[grammatim]

Sounds like you have a laptop where French (etc.) letters are assigned
to the keyboard when you press a "function" key to access them.

Or else, you've inadvertently switched away from your US keyboard. You
can toggle or cycle through the installed keyboards with Ctrl-LeftAlt.