Hi Bhagavan,
Thank you for contacting the Microsoft Community.
I can definitely help you in accessing your exam so you can reschedule it.
This issue occurs due to the following reasons:
If the candidate is having a browser issue
If not signed in using the correct Microsoft account
Having a duplicate profile
To access your appointment and reschedule, please follow the steps below:
You may try clearing cache/cookies and allow all third-party cookies (steps here).
Make sure you check preserve favorites website data and check both temporary internet files then click delete.
When accessing your dashboard to view your scheduled exam, kindly use InPrivate or Incognito browser.
Then sign in using the correct Microsoft Account used when you scheduled your exam.
Keep in mind that your exam should be rescheduled at least 24 hours prior to the original appointment to avoid forfeited exam fee.
For immediate assistance in rescheduling your exam, you may also reach out to Pearson Vue: Customer service :: Microsoft :: Pearson VUE as they have the ability to arrange your exam at your preferred time and date.
If the appointment is still missing after following my resolution recommendation, please share with us the details requested via private message so I can locate where the exam is scheduled and assist you further.
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 Messages. Thank you.