I've been thinking for a while and maybe there's one thing that you could have changed unnoticed..
Keyboards have an option to change 'language' e.g. when you press SHIFT + CTRL at the same time your keyboard can change into Russian settings (I'm just taking a random language).. If it changes to an other language the keys can have different positions (in case of Russian settings our alphabet doesn't even exist, they use Cyrillic writings).
How to solve/check it out? Your taskbar shows 2 icons - scroll to the right a bit (in my case NL and a keyboard).

Click on both and change it to the settings you'd like it to be (often just your language).
Hope this helped.