Hello Palani,
I am Jaspreet Singh.
The only way forward will be to contact Microsoft support directly and get the license linked to this device. This device needs to have a microsoft account active on it for this.
Here is how to get this done.
Click on this link : https://support.microsoft.com/en-us/contactus/
Click on windows
Click on get home support
In the subject window type in windows activation and press enter.
then click on "contact support" button at bottom.
Then in the next dropdown select windows.
Click on confirm button and you will get the option to contact support. (depending on time and location you will get the option to chat or request a callback or both)