If you are having problems with your keyboard layout you can type on the terminal:
Where "us" is the layout. It can be any valid identifier like br, cz, pt...
It won't help if you need to switch between layouts constantly, for this you should configure the file in /etc/X11/xorg.conf.d/10-keyboard.conf
Section "InputClass" Identifier "system-keyboard" Option "XkbLayout" "us,br" Option "XkbOptions" "grp:alt_shift_toggle" EndSection
In this example the default layout is American, and you can toggle to Brazilian Portuguese using "alt + shift".
There are a bunch of other options listed at /usr/share/X11/xkb/rules/base.lst.