To dream that you lose something, indicates that you may really have misplaced something that you had not realized yet. It may also be a signal for you to clean out and reorganize your life. Perhaps you are overwhelmed and distracted with the hustle and bustle of day-to-day life. Alternatively, losing something often coincides with a significant life change or waking issue.
To dream that someone else is lost, represents some unresolved issues or feelings pertaining to the person that is lost. Consider what aspect of that person you may have lost within your own self. Perhaps you need to recapture and re-acknowledge those aspects.