Mu touch bar is not working. Its totally blank

Not sure if you have tried Safe mode to troubleshoot.

Please try Safe Mode and see if you have same issue. https://support.apple.com/en-in/HT201262. Which may take more longer than your usual Normal boot & .

Note: Safe mode prevents your Mac from loading certain software as it starts up, including login items, system extensions not required by macOS, and fonts not installed by macOS. It also does a basic check of your startup disk, similar to using First Aid in Disk Utility. And it deletes some system caches, including font caches and the kernel cache, which are automatically created again as needed.