You basically need to run the installation again to rebuild the master database with the new collation. You cannot change the entire server's collation any other way.
See:
Update: if you want to change the collation of a database, you can get the current collation using this snippet of T-SQL:
SELECT name, collation_name
FROM sys.databases
WHERE name = 'test2' -- put your database name here
This will yield a value something like:
Latin1_General_CI_AS
The _CI means "case insensitive" - if you want case-sensitive, use _CS in its place:
Latin1_General_CS_AS
So your T-SQL command would be:
ALTER DATABASE test2 -- put your database name here
COLLATE Latin1_General_CS_AS -- replace with whatever collation you need
You can get a list of all available collations on the server using:
SELECT * FROM ::fn_helpcollations()
You can see the server's current collation using:
SELECT SERVERPROPERTY ('Collation')