HOW DO I GET THE TOGGLE BUTTON BACK TO THE UPPER RIGHT CORNER OF MY MICROSOFT CALENDER?

Hi

Are you using the Brower version or the Application?
If you're using the application it might be already installed.

Try to search for Outlook and check for "Outlook (New)"

If you open the mail app is the switch there?

Microsoft has instructions here if the switch is missing -

Toggling out of the new Outlook for Windows preview - Microsoft Support

Greetings! I'm Brandon, an Independent Advisor. It's essential to clarify that I am not affiliated with Microsoft as an employee. Therefore, I do not have access to your account information or other details that Official Microsoft Support might have access to. My role is to provide helpful guidance and assistance to the best of my knowledge and expertise.

If you are missing the "Try the new Outlook" toggle button on your Outlook Calendar, here are some steps you can try:

Clear Browser Cache: Sometimes, issues with the user interface can be resolved by clearing your browser cache and cookies. After clearing the cache, reload the Outlook Calendar and check if the toggle button reappears.

Switch Browsers: If you are using a specific web browser and the toggle button is missing, try accessing the Outlook Calendar using a different browser to see if the button appears there.

Check Microsoft 365 Settings: It's possible that Microsoft has made changes to the rollout of the new Outlook interface, and the "Try the new Outlook" toggle might be temporarily unavailable for certain accounts. Check the Microsoft 365 settings or configuration options to see if there are any settings related to the new Outlook experience.

Check with Microsoft Support: If you've tried the above steps and still can't find the toggle button, consider reaching out to Microsoft Support for further assistance. They might be able to provide more information about the availability of the toggle or any recent changes to the interface. you can contact them at https://vsa.services.microsoft.com/v1.0/redirect.html

Hope This Helps, and Don't Hesitate to reply below if you require any more Assistance :)