In order to start SQL 2008 R2 Express in Single User Mode you need to carry out the following steps.
1) Find out your SQL Instance Name. In my example its called VIM_SQLEXP.
2) Stop all the existing SQL services.
3) Open an Elevated command prompt
4) Change directory to the Binn folder in your SQL instance path. Mine is :
C:\Program Files\Microsoft SQL Server\MSSQL10_50.VIM_SQLEXP\MSSQL\Binn
Normally you would type
sqlservr.exe -m InstanceName
to launch SQL in single user mode. However in SQL 2008 R2 you need to add an extra bit
sqlservr.exe -m -sInstanceName
Note the -s and also how it is joined to the Instance Name.
You will now get loads of info come up on the screen. SQL is now launched in single user mode. Dont close this window