In some instances the administrator user name or password for the SonicWall appliance may be lost or corrupted. When this occurs there is no way to reset the password or discover it as an administrator, nor can SonicWall technical support provide any reset or recovery for lost administration credentials.
SonicWall appliances are first and foremost security devices, meaning they are not programmed with backdoors or other exploitable methods of access. While this has the downside of potentially locking an administrator out of their device, the benefit of a hardened and secure network outweigh these concerns and make sure your firewall and environment are fully protected from intrusions and attacks.
If the administration credentials for a SonicWall are misplaced then the only option is to reset to factory default and re-import your settings backup (if available and supported) or reconfigure from scratch.