lost

verb:unable to find something
- She realized she had lost her keys after searching the entire house.
verb:to fail to win (a game or contest)
- Our team lost the championship by a single point.
verb:to be unable to follow or understand something
- I'm sorry, I lost you after you mentioned the new task.
adjective:unable to find one's way; not knowing where one is
- You look lost, can I help you?
adjective:that cannot be found or created again
- She's trying to recapture her lost youth.