Keyboard are not working

@shamnujr make sure that you checked your device manager and make sure that the keyboard is not disabled by any software etc. Start your OS in safe mode and see of that makes a difference. You always want to rule out bad software first. You also want to reinstall the keyboard driver. IF you find that all of that is setup properly, it is entirely possible that this is a failed keyboard.

For most of the Lenovo computer, you can actually download the service manual. Since you did not give us the details for your computer, we can only provide you with the basics. Go to this site where you select the series and the subseries to then get to the service manual. Use that to replace your keyboard. Keep in mind that most keyboard now are considered part of the top case since it maybe rivetted or glued into the top case. Again, this will depend on your exact model.