Unable to find server name of SQL Server After installing SQL Server 2008 R2, it wants a server name.

I tried SQLCMD -L on cmd, but it shows the error below:


  Data source name not found and no default driver specified


What am I doing wrong?

Any kind of help will be appreciated.
You can go with two methods as given in answers to the Stack Overflow question How to find server name of SQL Server Management Studio.

User PoweredByOrange:
Open up SQL Server Configuration Manager (search for it in the Start menu). Click on SQL Server Services. The instance name of SQL Server is in parenthesis inline with SQL Server service. If it says MSSQLSERVER, then it's the default instance. To connect to it in Management Studio, just type  . (dot) OR (local) and click Connect. If the instance name is different, then use .[instance name] to connect to it (for example if the instance name is SQL2008, connect to .\SQL2008).
Also make sure SQL Server and SQL Server Browser services are running, otherwise you won't be able to connect.

or:

User sansa:
Run this Query to get the name
SELECT @@SERVERNAME