CLI Doesn't Work

After the issue of the publuc IP and the reset of the adress I can't acess my Instance of Ubuntu. My private key is refused, I generate a new pair of keys, still refused. The documementation of Oracle says to try troubleshooting using the Cloud Shell conection that allegedly doesn't require extra autentication, but ask for a login and a password that i never set. I don't know what do next, seems I lost all of my data in the Instance