i asked bagstone(a moderator) and he said all postcount is gone.
Can confirm, that was the response I received before the closure, when the Curse developers were in charge. Of course now there's new people in town, and maybe some new hope (i.e., maybe it was just too difficult but not impossible - I don't have insight into that kind of backend programming of DiabloFans). And I wouldn't get my hopes up.
Oh, sorry for missing context. We're talking about accounts that have been basically deleted due to the Fandom purchase in December/January or so. Every DFans user received an email with a link they had to click to consent to Fandom taking over the data - if you didn't click that link, apparently your account got deleted. I'm not sure if accounts were ever restored after this (if so that was probably Curse account service, I know nothing about this), but the posts are gone.