Special character from keyboard isn't showing up

Hello!

Yesterday I got the following strange problem, which I can't find solution for:

When I want to type left curly bracket from keyboard with usual shortcut Ctrl+Alt+B, it doesn't show up in any application, including Google Chrome and Wolfram Mathematica. B key alone works perfectly fine and also Ctrl+Alt+ any other key works perfectly fine. This problem happened out of nowhere. What could be the problem? What to do to solve this? I am desperate now since I spent a lot of time looking for solution, but nothing helped.

Sincerely,
Nikola

Now the combination of keys works and problem seems to be solved, again out of nowhere. I didn't do anything to solve the problem. Very strange.