I am using SQL Server 2005. When I execute DBCC USEROPTIONS, I see the language as romana and dateformat as dmy.
I want the language to be
You can reset the language by using the below syntax
set language 'us_english'
In order to view all the languages and their date format try this one
select * from sys.syslanguages
If you need to permanently change the language then
SecurityLoginsPropertiesEnglishThis change will persist even after you restart your SSMS
Before
DBCC USEROPTIONS
is returning something like this:

USE [master]
GO
ALTER LOGIN [UserLogin] WITH DEFAULT_LANGUAGE=[us_english]
GO
Next - reconnect to SQL (logout -> login).
After
You will get this:
