How can I use my laptop keyboard as other laptop keyboard?

One option if both computers still work, is to use a program like synergy. It allows you to use a keyboard and mouse from one computer to control another.

http://synergy-project.org

This one works on any machine with ssh X forwarding (yes, even a phone):

First, install x2x on the machine you want to control (the remote machine), and then on the local machine, run:

ssh -X remote_machine.local x2x -west -to :0.0 

where remote_machine.local is the hostname or ip of your remote machine. this command will extend your local machine's display to the left of the screen, "attaching" the remote machine's display, so moving your cursor to the left, past the left edge of your local machine, will begin to control the cursor on the remote machine

You can use -east, -north or -south as well. If you want to do this from within a window, you could look into running x2x from an Xnest window.

related: https://raspberrypi.stackexchange.com/questions/4253/forward-mouse-and-keyboard-input-to-x-session