Impossible d'accéder a WD My Cloud

bonjour à tous,
j’ai le message suivant “Utilisateur du dispositif introuvable. (400015)” de plus il ne reconnait plus mon mot de passe pour accéder à mes dossiers et documents, je n’y comprend plus rien … Help!

It would help if you can provide more information. For example:
What specific My Cloud model are you using?
Where are you receiving this error? In the My Cloud Dashboard or through some other method like remote access using the MyCloud.com web portal?
When connected to the same local network as the My Cloud, are you able to access your files using Windows File Explorer or Mac Finder?
Can you access the My Cloud Dashboard?

Generally one configures the single bay/single drive My Cloud using the My Cloud Dashboard. One can configure User access to the My Cloud through the My Cloud Dashboard including the User password to access Shares. The MyCloud.com username and password is separate from the username and password one uses to access the local network My Cloud.