In my HP laptop, Keyboard is not working properly,
I am unable to type some keys like (a , g, [,) and sometime it works good.
Some keys are always pressed like kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk.
How can i fix it?
Depending on your model, replacement keyboards can be quite cheap and they are easy to replace. Go onto the HP support website, enter your laptop model number and download the maintenance and servicing guide, in there you will find instructions with pictures/diagrams on how to replace the keyboard. It is a very straightforward and simple procedure.
If you do decide to go with an external keyboard, you might be able to get away with disconnecting the inbuilt keyboard and pointing stick cables to disable the keyboard.
It sounds like there is physical damage to the keyboard. You'll need to replace it. Laptop keyboards are actually quite easy to replace, but finding the part might be tricky. Looking around on eBay is probably your best bet.