Impossible to launch Studio 2021, "Impossibile avviare il servizio"

Impossible to launch Studio 2021, the message is Impossibile avviare il servizio "Sdl.TransaltionStudio.Api.Projectmanagement.IProjectManagementService".

Last time it happened I renamed something (don't remeber what, a folder?), but all the projects disappeared.

Is there a way to sort this out without losing the actual project I'm working on?

Thank you