You can try to boot into safe mode.
This will use automatically the admin account.
If this would work then you could create an new user account and could use this new account for login.
Please check also this MS knowledge base article:
Error message when you log on to a Windows Vista-based or Windows 7-based computer by using a temporary profile: "The User Profile Service failed the logon. User profile cannot be loaded" http://support.microsoft.com/kb/947215/en-us
If this will not help you then you would need to restore the whole system using recovery disk ;(