Using a keyboard short cut it is possible to change to English keyboard from
the default language setting, which in my case is Norwegian. For example,
pushing the sign "ø" on the Norwegian keyboard (third row, third from the
right) then returns ";"

I mainly use the keyboard to navigate, rather than the mouse, and by mistake
I often happen to change the language setting of the keyboard. To cancel that
setting and return to the default language setting I have to exit the program
(for example Word, or Powerpoint) and then open it again.

I have tried many times to find out what it is I am doing when I mistakenly
change the keyboard language setting, but till now without success. I think
it is something with Ctrl + ..., or Ctrl + ... + ... (where the latter is a
key at the right hand side of the letter keyboard).
Does anyone know this keybard command?