If Office Web Apps (OWA) stops working, you may need to rebind SharePoint to the Office Web Apps server. You do this by following these steps.
- Open up the “SharePoint 2013 Management Shell” on one of the application servers using “run as administrator”.
- Remove all previous bindings by running the following command.
- Set the WOPI zone by running the following command.
set-spwopizone -zone external-https
- Recreate the binding by running the following command (assuming the office web apps server is prod-owa1).
New-SPWOPIBinding -ServerName “prod-owa1”
- Then start a full search crawl on all the content on the farm.