Until last week, pressing Ctrl + right / left arrow would take me to the
furthest left/right cell in a data region, it now shifts worksheet one page
right or left (i.e. to the next unviewed column on left / right of viewable
screen), I think this used to be the Fn + right / left arrow. Keyboard
language settings all appear to be correct.

Any suggestions as to how to reset this shortcut?

Thanks