If you have trouble because cannot login and cannot accessible after you Restoring a Database, you must change owner and connect between user login with user Database.
The following steps are below : 

1. Check the orphaned users used this query: 

USE change_db_name>; 

EXEC sp_change_users_login 'Report'

2. Change owner of a database:

ALTER AUTHORIZATION ON DATABASE::TO MyLoginUser>

3. Map the user Database with user login : 

SET NOCOUNT ON

USE change_db_name>

GO

DECLARE @loop INT

DECLARE @USER sysname

DECLARE @sqlcmd NVARCHAR(500) = ''

IF OBJECT_ID('tempdb..#Orphaned') IS NOT NULL 

 BEGIN

  DROP TABLE #orphaned

 END

CREATE TABLE #Orphaned (UserName sysname,IDENT INT IDENTITY(1,1))

INSERT INTO #Orphaned (UserName)

SELECT [name] FROM sys.database_principals WHERE [type] IN ('U','S') AND is_fixed_role = 0 AND [Name] NOT IN ('dbo','guest','sys','INFORMATION_SCHEMA')

IF(SELECT COUNT(*) FROM #Orphaned) > 0

BEGIN

 SET @loop = 1

 WHILE @loop Note :  = Change this value to the Database

 = Change the value to sa or the Administration of user.

4. Do the steps point 1 - 3 for all of Database you have.