WordNet sense 1 (deeply absorbed in thought):

bemused, preoccupied

WordNet sense 2 (exhibiting or characterized by careful thought):

thoughtful

WordNet sense 3 (no longer known; irretrievable):

forgotten

WordNet sense 4 (incapable of being recovered or regained):

irrecoverable, unrecoverable

WordNet sense 5 (perplexed by many conflicting situations or statements; filled with bewilderment):

baffled, befuddled, bewildered, confounded, confused, mixed-up, mazed, at sea

WordNet sense 6 (full or difficulty or confusion or bewilderment):

perplexed

WordNet sense 7 (having lost your bearings; confused as to time or place or personal identity):

disoriented

WordNet sense 8 (not having position or goal definitely set or ascertained):

unoriented

WordNet sense 9 (surrendered as a penalty):

forfeit

WordNet sense 10 (destroyed physically or morally):

ruined

WordNet sense 11 (in danger of the eternal punishment of hell):

doomed, unredeemed

WordNet sense 12 (not used to good advantage):

wasted, squandered

WordNet sense 13 (not able to be found):

missing

WordNet sense 14 (no longer retained):

gone

WordNet sense 15 (unable to function; without help):

helpless

WordNet sense 16 (not caught with the senses or the mind):

missed

WordNet sense 17 (difficult to understand):

incomprehensible, uncomprehensible