How did you configure the data and log file paths during the setup process? If you specified an alternate path, the data and log files would be created in the alternate path. The details about why the service failed to start would be located in the SQL Server Error Log file. You can find the location of that file by opening the SQL Server Configuration Manager (Start->All Programs-> Microsoft SQL Server 2008 R2->Configuration Tools->SQL Server Configuration Manager) and then click on SQL Server Services and right click on SQL Server (<Instance Name>) and open Properties. Click Advanced and then click the drop down on Startup Parameters. You want to find the -e parameter value, which specifies the path to the ErrorLog:
-eC:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Log\ERRORLOG
Open that file up and post the contents back here. If it doesn't exist, you have a failed install and need to remove it and try again. The -d and -l parameters specify the path to the data and log file for the master database.
Jonathan Kehayias
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