Getting an error like this after you start SQL in single user mode can be frustrating: 

This happens to me sometimes when I am attempting to reset passwords of instances. Here are the steps you can take to get by this error (“Run as Administrator” should be selected for all command below) :

1. Stop the SQL Server Service:
   
   net stop MSSQLSERVER

   1	net stop MSSQLSERVER

2. Start the SQL Server Service using the switches below. The service will not fully start and the “service is starting…” message will remain in the command window. Once this message is displayed you can move on to step 3:
   
   net start MSSQLSERVER /c /m /T3608

   1	net start MSSQLSERVER /c /m /T3608

3. Either open Management Studio and connect to the instance, or open a new CMD window to use SQLCMD.
4. Once you’ve completed the necessary changes the SQL Server Service will need to be forcibly stopped. Either end the process in task manager or use the following command in the windows CMD window:
   
   taskkill /IM sqlservr.exe /F

   1	taskkill /IM sqlservr.exe /F

5. Now SQL can be started normally.