ArcGIS Online is telling me that I don't have access to all my old feature services. If I'm not mistaken it also no longer has the option to add a new feature service. Did something change in the last 24 hours?
Just a couple of of follow-up questions:
Where you on a trial/free account? - After the trial ended, that might be impacting your access on the free account
If this is ArcGIS Online through your work - I would recommend reaching out to your administrator! It actually looks like your permissions may have been changed, or you were assigned a different role. You may need to ask them if you were assigned incorrect permissions.