How to return multiple rows in case when condition?

Question

I want to display the list of product names owned by a company.If no products found it should return a string like "NO PRODUCTS FOUND'
The query I wrote working well but when the condition does not satisfy Its not returning  "NO PRODUCTS FOUND''. Can someone help me how can I do this?
declare @Country varchar(100)='Netherlands'
SELECT     CASE WHEN count(table4.ProductName) >0 THEN table4.ProductName 
               ELSE 'NO PRODUCTS FOUND' END AS Product_list
FROM              table2 INNER JOIN
                      table1 ON table2.AccountID = table1.AccountID INNER JOIN
                      table3 ON table1.[company_ID] = table3.[company_ID] INNER JOIN
                      table4 ON table4.ProductID = table2.ProductID
WHERE    
                     table1.[country] IN (@Country)) AND table4.ProductID IN (24410, 24413, 24418, 24383,                           24384))
GROUP BY table4.ProductName 

Answer 1

Your DDL does not match your query.
You also supplied no test data.
You're using INNER JOINS to enforce relationships that may not exist. You're using a WHERE clause to do the same.
Try this:
DECLARE @table1 TABLE (accountid int not null, productID varchar(20), company_id int)
DECLARE @table2 TABLE (accountid int not null, country varchar(20))
DECLARE @table3 TABLE (company_id int not null, company_name varchar(20))
DECLARE @table4 TABLE (productID int not null, productname varchar(20))
INSERT INTO @table2 (accountid, country) VALUES (1, 'Netherlands'),(2, 'Netherlands'),(3, 'Germany')
INSERT INTO @table1 (accountid, productID, company_id) VALUES (1,24410,1)
INSERT INTO @table3 (company_id, company_name) VALUES (1,'one company'),(2,'two company'),(3,'three company')
INSERT INTO @table4 (productID, productname) VALUES (24410,'a product')
DECLARE @Country varchar(100)='Netherlands'
SELECT t3.company_name,
CASE WHEN count(t4.ProductName) > 0 THEN t4.ProductName
ELSE 'NO PRODUCTS FOUND'
END AS Product_list
FROM @table2 t2
INNER JOIN @table3 t3
ON t2.accountid = t3.company_id
LEFT OUTER JOIN @table1 t1
ON t2.accountid = t1.accountid
LEFT OUTER JOIN @table4 t4
ON t1.productID = t4.productID
WHERE t2.country = @Country
GROUP BY t3.company_name, t4.productName