Hi Salma Repole
Try following this step below to dismantle your keyboard
[guide|60774]
there is a lvds cable which is connected to the mainboard. Disconnect it carefully and clean up your keyboard.
[image|1451894]
Use an eraser to rub on the LVDS cable connector of the keyboard module and reconnect it back.
Test your keyboard, one good link to test and spam the keys...
http://www.keyboardtester.com/
Launch It and test...
If all fails, consider getting a replacement keyboard module from ebay.
https://www.ebay.com/itm/New-Asus-Chromebook-C201-C201P-C201PA-C202-C202S-C202SA-Series-Keyboard-US-Black/173294682143?hash=item28592b001f:g:48UAAOSwSata5qSY