Hi Manisha,
This forum doesn't support questions about certifications and exams. There is another forum (Microsoft Training Support) for this. Please ask there.
https://trainingsupport.microsoft.com/en-us/newthread?threadtype=Questions&forum=mcp
You are confusing me with your dates... if you completed your exam successfully on the 31st of December... then you should be able to download it. If it was today (31. January), you have to be patient as it might take up to 48h to have the certifications wholly provided within the portal.
I hope my answer is helpful to you,
Your
Bjoern Peters
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