@M.khan Welcome to Microsoft Q&A forum!
Sorry to hear that you are having issues with workbench UI.
Just to confirm, Have you made any changes to your workbench recently? I would suggest you, please check the logs by following Azure Blockchain Workbench Preview troubleshooting guide and see if it helps to identify the root cause?
Please see the similar issue discussed here which occurred due to the password for docker repo was missing in the app service configuration settings
I also suspect that, this issue might have occurred due to the service interruption. Please see Azure status history for more details.
Do let us know if that helps or have any further queries.
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