i have uodated my mbp early 2011 to sierra recently (few days ago). suddenly today the trackpad stopped working…i have used the built-in controls with the keyboard to go into system preferences- accessibility -mouse &trackpad- deselect “ignore built in travkpad when mouse or wireless trackpad is present “ - options- deselected “ignore built in travkpad when mouse in”
to move the pointer:
u - left
o- right
i - click
k- down
8- up