How far back is it possible to retrieve Battle.net characters?

Solution 1:

Alas, there is no hope: whole Diablo II Battle.net accounts expire after three months of inactivity.^{1 2} Once expired, the username is available for others, and your details are deleted in the next maintenance cycle. New B.net accounts need two hours of use in the first 48 hours to activate.

New characters need two hours of use in the first ten days to activate. Individual characters expire after 90 days of inactivity (not performing an in-game action).³ Technically, Blizzard can purge these characters at any time, but they have been lax⁴—expired characters are available on your account until another player recycles their names, or your D2 B.net account is deleted altogether.

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