Unable to create or add a store. Event ID: 0 & Event ID:1
Checking the event viewer on the Storefront server gives the following events- 



Also, unable to browse an existing store. "The webpage cannot be found."


 

Both the Event IDs are very descriptive and tells: Application pools cannot be started unless the Windows Activation Service (WAS) is running.
So, check the Services Console on the Storefront and ensure that both, Windows Process Activation Service and World Wide Web Publishing Service are started.
If not, start these services and the Application Pool will start.

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Problem Cause

Windows Process Activation Service and World Wide Web Publishing Service are in a Stop and Disabled state.