After I’ve deleted some values (do not remember which) in my project configuration (in the Developer Console) I cannot deploy an app to a Compute E
Maybe you deleted your App Engine service account. To create it again, you can go to the Permissions section of your project and add a new member with the email YOUR-PROJECT-ID@appspot.gserviceaccount.com (replace with your real project id) and "Can Edit" permissions.
Maybe you're not authenticated to your project anymore? Have you tried to reauthenticate using gcloud auth login
?
If you're authenticated but happen somehow to delete default Google AppEngine service account (app_id@appspot.gserviceaccount.com), you won't be able to recreate them yourself. You will need to file a support ticket with Google and ask them to recreate the default service account for you.
Finally, you can create new project and deploy your application there but of course this comes at a price/time.