Can you access you Autodesk account? In that case I would create support ticket and ask Autodesk personnel to have a look.
It might be that the service is/was offline (e.g. maintenance) or it might be that somebody took away your rights (e.g. your IT Manager). In a worst case scenario it might be that somebody managed to get hold of your account details and locked you out.
Louis

Please mention Revit version, especially when uploading Revit files.