The Oxford Thesaurus An A-Z Dictionary of Synonyms - irretrievableadj.

1) non-retrievable, unretrievable, unrecoverable, irrecoverable, unsalvageable, unsavable, lost, irreclaimable: The data that was deleted is now irretrievable. 2) irreparable, irremediable, uncorrectable, unrectifiable, irredeemable, irreversible, irrevocable: The radiation from the atomic blast did irretrievable damage.