There is no option to reset the DSM user account. I would suggest to verify you are using the correct username and that the username is case sensitive. I have seen it before where the username is typed as "admin" when it is actually "Admin".
Can you try rebooting your Data Collector server to verify that the process are up and running? Or can you send me a private message so I can open a case and check your system logs? Include your name, email address, and Compellent system number.
If my answer was helpful, please click: Kudos Forum Member since 2012 #iwork4Dell