http://www.mssqltips.com/sqlservertip/2682/recover-access-to-a-sql-server-instance/
The process to get back up and running is quite simple. Log in to the server where SQL Server is running, as an account with local Administrator privileges. Download and extract PsExec.exe (http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx). Run the command prompt (i.e., cmd) as an Administrator. Run the following command, adjusting for your actual path to Management Studio:
PsExec -s -i "C:\Program Files (x86)\Microsoft SQL Server\110\Tools\Binn\ManagementStudio\Ssms.exe". It worked!
(issuing the PsExec command from the right directory. In my case, it is: C:\Users\CK\Downloads\PSTools\PsExec -s -i.....)
