My laptop kybaord not working why

@liliameftah sometimes keyboards just fail. There is not a lot of why that we can answer, unless we can take is apart. It could be a bad membrane, bad wiring, bad circuitry etc. Could be a bad flex cable and yes, it could even be a motherboard error.

If yours does not work, and if you can use an external keyboard,, time to change it. Of course, make sure that it really is not working and that this is not a software settings issue.

Once you ensured it is the keyboard, use the HP 640 ProBook G3 Maintenance And Service Guide and page 47 will show you exactly how to change it. Replacement keyboards are readily available at many online stores.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!