Your attachment did not work. My recommendation would be to contact support in an instance like this. You're paying for support and maintenance from them, you may as well use it!
Hi O Ghosh,
Are all of your Tableau services running? The Tableau page has a Status page you can check. You also may want to check the time settings on the server to make sure they are in the proper date and time zones.
You may also want to check current tasks to see if anything is stuck.