Hi Srinivasaprasad
Thank you for contacting the Microsoft community.
I recognize that you haven't received the 50% discount after completing the AZ-900 Fundamentals from MVTD event, and I know how important it is for you to obtain this voucher for exam purposes. Please allow me to assist you and provide the necessary information you need.
Since you mentioned that you haven't received the 50% voucher yet, please be informed that the voucher code will be sent to you via the "Thank You" email within 5 business days (excluding Saturdays and Sundays) after completing the training. Since the last day of your training was on the 20th of August, you should expect the Thank you email which incorporates your 50% on 27th of August.
To ensure you don't miss anything, kindly suggest double-checking the email you are looking at, as the Thank You email will be sent to the address you used to register and complete the MVTD event. Additionally, please check your spam/junk folder as the thank you email may route there.
If you have followed the above advisements and still have not received the "Thank You" email as of 27th of August on your registered email address, please inform me via the private message I have initiated along with the requested information. Kindly send us the requested information so I can forward this concern to our support team for further investigation. Please refer to the sample of the thank you email received by eligible candidates below:

To obtain more details about the MVTD discount, feel free to check out this. sticky post, or you can run to the Microsoft Virtual Training Day event page, where you will find useful details in the FAQ section.
Kindly let me know if further assistance or clarification is needed so that I can be of additional help if necessary.
I look forward to your response. Please note that if no response is received after two business days, the case will be closed and locked. After the case is locked, we will no longer be able to respond, even through private message. Thank you.