The key combination you're referring to probably switched your keyboard layout.
For examply, I use Dvorak to type, but to switch over to regualar QWERTY, my family presses Alt+Shift.
Note, that's because I have it set up that way. Your combination might be different.
Control Panel --> Search "languages" --> Click "Change keyboards or other input methods" --> Click the button that says "Change keyboards"
If you see anything other than plan "US" or "English" under "Installed Services", remove it.