Use the following script
USE [master]
SET NOCOUNT ON;
-- Create a temp table to hold orphaned accounts
if OBJECT_ID('tempdb..#Orphans') is not NULL DROP TABLE #Orphans
CREATE TABLE #Orphans (
ID INT NOT NULL IDENTITY,
DBName NVARCHAR(MAX) DEFAULT NULL,
Username NVARCHAR(MAX),
userSID NVARCHAR(MAX)
)
-- For each database get orphaned accounts
EXEC sp_MSforeachdb 'use [?]; insert into #Orphans (Username,UserSID) EXEC sp_change_users_login ''REPORT''; update #Orphans SET dbname = ''?'' where dbname is NULL'
-- Remove DBs that are not ONLINE or that are READ_ONLY as we can't alter them.
DELETE FROM #Orphans WHERE NOT [DBName] IN
(
SELECT name
FROM sys.databases
WHERE state_desc = 'ONLINE' AND is_read_only = 0 -- Databases that are ONLINE and NOT Read_Only
)
-- Loop through all remaining orphans and attempt to un-orphan them
DECLARE @CurRow INT = 1
DECLARE @EndRow INT = (SELECT MAX(ID) FROM #Orphans)
DECLARE @SQLCmd NVARCHAR(MAX)
WHILE @CurRow <= @EndRow
BEGIN
SET @SQLCmd = (SELECT 'USE [' + DBName + ']; EXEC sp_change_users_login ''UPDATE_ONE'', ''' + Username + ''', ''' + username + ''';' FROM #Orphans WHERE ID = @CurRow)
SET @CurRow = @CurRow + 1
PRINT @SQLCmd
EXECUTE (@SQLCmd) -- re associate the login with the user account
END
-- Drop temp table holding orphaned accounts
if OBJECT_ID('tempdb..#Orphans') is not NULL DROP TABLE #Orphans
