How to correct SQL-Server installation with wrong language? What is the best way to re-install a SQL Server that was installed using a wrong language without losing any configuration?


Should I install a second instance parallel to the default instance - here I do not know if this is anyhow possible at all if using a different language? 
Or should I install a second installation of Sql Server (as if it were two different Versions)?
Alternatively I could of course uninstall the old and install a new Sql Server using the correct language.


Independent of the way to go, as you can imagine, I definitely want to avoid doing all the maintenance work for creation of Logins, Users, Permissions, Alerts, Operators, Jobs etc. again. Is there a good approach to achieve this?
This can be done from the SSMS GUI.  Right click on the instance in object explorer and go to properties.

From there navigate to the Advanced page.

There is a drop down item there for Default Language.

Alternatively, if you know the language code you can do it via tsql

EXEC sp_configure 'default language', 0 ; 
GO  
RECONFIGURE ;  
GO


where 0  is English in this case.

See https://msdn.microsoft.com/en-GB/library/ms190682.aspx

You may also need to update or change the default language of logins via their properties page.