All of these instructions should be done as a database admin, with the restored database selected.
First, make sure that this is the problem. This will lists the orphaned users:
EXEC sp_change_users_login ‘Report’
If you already have a login id and password for this user, fix it by doing:
EXEC sp_change_users_login ‘Auto_Fix’, ‘user’
If you want to create a new login id and password for this user, fix it by doing:
EXEC sp_change_users_login ‘Auto_Fix’, ‘user’, ‘login’, ‘password’
http://www.fileformat.info/tip/microsoft/sql_orphan_user.htm