I can't use my laptop keyboard?

Take the battery out unplug it push and hold the button for 40 seconds with it unplugged and the battery out then put the battery back in and restart it see if the keyboard works then if not the ribbon cable on the keyboard has fallen out of the pinch clip if you just bought it I'd be returning it in a heartbeat if not you need to go on YouTube and see how to replace the keyboard that's a very simple procedure and you'll see the little pinch clip when they uninstall the keyboard

Try external USB keyboard.