Hello HarshBhatia,
From your post it appears you are having some issues with all the keys on your Lenovo keyboard being recognized.
Try starting up the system in what is called safe mode. This will help isolate this issue.
To start in safe mode, begin with the computer powered off. Follow the directions found here, depending on what type of Mac you have: How to use safe mode on your Mac - Apple Support
The computer will take longer to start in safe mode, and the screen may have some distorted video as it starts up. This is normal. Once you are logged in, use the keyboard and test to see if the issue continues.
If everything seems to work as expected, go ahead and restart the computer normally and test again. Starting in safe mode forces the computer to run some disk checks similar to First Aid. This can resolve some issues.
If the issue remains, we would recommend reaching out to the keyboard manufacturer. They are going to be in the best position to assist with their device.
Have a good day.