Unavailable means not able to be had or reached. Currently unavailable, unavailable for comment, temporarily unavailable.
Unavailable for comment is the standard formula when somebody has declined to speak or could not be reached, and it deliberately does not say which. In shops it means out of stock. Of a person, emotionally unavailable is now a fixed phrase meaning unwilling or unable to form a close attachment. Note available; and that unavailable is almost always temporary in implication.
unavailable is a state of not being obtainable.
Middle English
available
English
available
English, today
unavailable
From un- + available. available comes from Middle English available, avayllable, avayleable, equivalent of avail + able.
Etymology from Wiktionary, CC BY-SA