Lost
Part of speech: adjective
Definition: When one is unable to find his or her way
Part of speech: verb
Definition: To cause (something) to cease to be in one's possession or capability due to unfortunate or unknown circumstances, events or reasons.
Example sentence: 'Tis better to have loved and lost than never to have loved at all.
Unrecoverable
Part of speech: adjective
Definition: Not recoverable.