Keyboard not working since update

Hi

I have a Macbook Pro late 2011 and updated it a while ago with the newest Sierra software (10.12.4). Since this update though my built-in keyboard isn't working anymore at all as soon as I logged into my Laptop. Strange enough it still works on my Windows partition (boot camp) and in the login screen, but stops working as soon as I hit the enter key after typing my password. The mouse pad keeps on working, so some stuff I can still do, but really not a lot. I already tried out to change settings but without effect.

I'm looking forward to your answers and hope you can help me.

Greatings Patrick