Why did the keys on my laptop stop working?

Question

Keyboard

Notebook Lenovo V560. The other day the keys suddenly stopped working: start, PgUp, PgDn and Num-8. On the clave did not pour anything. It's just that the computer stopped responding to pressing these buttons. The problem is not software, I checked. Klava disconnected and reconnected. Removed the buttons. I can’t understand why the buttons suddenly died, which are not even next to each other.

Answer 1

Everything that can be seen and cleaned - you have done. There are no crumbs under the keys, nothing interferes mechanically, the cable is in order.
All that's left is the tracks. Here is one somewhere gave a crack. And 3 keys fell off.
The keys are not very responsive - either use it this way, or replace it, or connect an external USB at home.

Answer 2

Interview everyone who had access to a laptop, maybe it will turn out who lil)