Thank you for using our online answers forum. I am sorry to hear you are having issues getting logged into your Sling account, at this point we would need some more information to help determine the exact culprit. Why did you switch accounts in the first place, were you having issues getting logged into that account as well? Have you tried resetting your password?
Here is a link that might help troubleshoot your issue further.
Hope this helps, feel free to reply back with any other questions or concerns you are having.
The Sling Moderation Team