MacBook Air 2017 - Keyboard not working

Hello.

The keyboard of my 2 years and 2 months old MacBook Air 2017 suddenly stopped working about a month ago. Since then, when I try to type with the internal keyboard, it either doesn't react at all, or just gives me signs, like roots or other symbols. Also, when I try to click with the click pad, or even using a bluetooth mouse, the reaction is the same as using a "right click". What is weird is that after I did a software update, until I turned the macbook off, everything was working perfectly fine... Like nothing ever happened. But after turning it off and back on, nothing was working again. I can't imagine that it's a hardware issue? Could that even be? What could be the reasons for these issues? Could I do something by myself? Because I'm a student, I can't afford to go to the store and get an expensive repair or even buy a new MacBook... So I'd really be happy if I could get mine to work again... Please help me...