Supervisor missing after I stopped server management

I have Home Assistant installed as VM on a Synology VMM, working for a while.
I had the unhappy idea to Stop from Configuration/Server Controls/Server Management and now, even after restarting the Home Assistant VM, I have Home Assistant running without any add-on and Supervisor missing.

Once I access the Supervisor from the portal I get the error Unable to load the panel source: /api/hassio/app/entrypoint.js.
How can I restore the previous situation and reactivate the supervisor, if this is the problem?