This is awfully nasty... I strongly recommend that if you want to treat each address line separately, that you store it correctly in the first place. Instead of continuing to do what you're doing, add the additional columns, fix the existing data once (instead of "fixing" it every time you run a query), and then adjust the stored procedure that does the insert / update so that it knows to use the other columns.
DECLARE @Address TABLE(id INT IDENTITY(1,1), ad VARCHAR(MAX));
INSERT @Address(ad) SELECT 'line 1
line 2
line 3
line 4'
UNION ALL SELECT 'row 1
row 2
row 3'
UNION ALL SELECT 'address 1
address 2'
UNION ALL SELECT 'only 1 entry here'
UNION ALL SELECT 'let us try 5 lines
line 2
line 3
line 4
line 5';
SELECT
id,
Line1 = REPLACE(REPLACE(COALESCE(Line1, ''), CHAR(10), ''), CHAR(13), ''),
Line2 = REPLACE(REPLACE(COALESCE(Line2, ''), CHAR(10), ''), CHAR(13), ''),
Line3 = REPLACE(REPLACE(COALESCE(SUBSTRING(Rest, 1, COALESCE(NULLIF(CHARINDEX(CHAR(10), Rest), 0), LEN(Rest))), ''), CHAR(10), ''), CHAR(13), ''),
Line4 = REPLACE(REPLACE(COALESCE(SUBSTRING(Rest, NULLIF(CHARINDEX(CHAR(10), Rest) + 1, 1), LEN(Rest)), ''), CHAR(10), ''), CHAR(13), '')
FROM
(
SELECT
id,
ad,
Line1,
Line2 = SUBSTRING(Rest, 1, COALESCE(NULLIF(CHARINDEX(CHAR(10), Rest), 0), LEN(Rest))),
Rest = SUBSTRING(Rest, NULLIF(CHARINDEX(CHAR(10), Rest) + 1, 1), LEN(Rest))
FROM
(
SELECT
id,
ad,
Line1 = SUBSTRING(ad, 1, COALESCE(NULLIF(CHARINDEX(CHAR(10), ad), 0), LEN(ad))),
Rest = SUBSTRING(ad, NULLIF(CHARINDEX(CHAR(10), ad) + 1, 1), LEN(ad))
FROM
@address
) AS x
) AS y
ORDER BY id;
Denis' PARSENAME() trick is much tidier of course, but you have to be extremely careful about using a replacement character that is truly impossible to appear in the data naturally. The carat (^) is probably a good bet, but like I said, you need to be careful.
There are also software packages out there that are really good at scrubbing address and other demographic data. But cleaning up the data entry is the most important thing here that I'll continue to stress... if each address line needs to be treated separately, then store them that way.