Hello, Vijayaraghavan.
Welcome to Microsoft Community, here your request will always be well received.
We understand from your post, are not able to download your Certification from your Dashboard.
Please keep in mind that once you have completed and passed your Exams, it takes from 3 to 5 business days for the Certification to appear on Your Dashboard.
In order for us to be able to provide you with further assistance, we have created a Private Message for you to send us some additional information.
To access this space, please go to the link on the top right corner as shown in the image below. Once you provide this information, we will continue with the proper process.

We are looking forward to your response. If no response is received we will proceed to close and lock the case and private message within two business days.
We hope you have an excellent day,