IPA: /ˌʌn.rɪˈkʌv.ər.ə.bəl/
KK: /ʌnˈrɛkəvərəbəl/
Something that cannot be recovered or restored.
The data was lost and is now unrecoverable.
Unrecoverable → It is formed from "un-" (meaning not) and "recover" (from Latin "recuperare", meaning to regain or recover) and "-able" (meaning capable of). The word "unrecoverable" means not capable of being regained or recovered.
Think of 'not' ('un-') being able to 'regain' something ('recover') — that's why 'unrecoverable' means something that cannot be regained.