Do you have another keyboard profile installed on that machine? It’s possible that you hit one of the Language Bar toggles (such as Alt+Shift). See if you have an indicator to the immediate left of the task bar notification area (which is the right side of the task bar, where the time shows up if you have the clock turned on, along with icons for many running programs). The indicator will be two uppercase letters, such as “EN” for English. If it’s there, and you click on it, a context menu will pop up to allow you to switch the keyboard profile. Make sure that the appropriate profile is selected – likely “English (United States)” for you.