How do I reset my keyboard layout?

Try:

setxkbmap us

(Replacing us with the keyboard layout you want). If using a variant (e.g. intl), try

setxkbmap -layout us -variant intl

Here's a list of keyboard layouts.

Check current layout and options:

setxkbmap -print -verbose 10

Reset layout to US and reset options:

setxkbmap -layout us -option

(Without the empty -option parameter, no options would be reset.)

Use the first command to check the result.