Update.

Got the answer from support: https://i.imgur.com/hgKSbrE.png

So... we have traded in 2017 and now in 2019 he marked trade as fraudlent. But he left the localbitcoins and there's no contact with him and he didn't contact me before. I am stucked, but there's solution: I have to find some 2 years old invoices, which might be hard. I have asked some questions LBC support, waiting their reply, mainly how can I contact him, as they have disabled chat.

I see that's a method to block all accounts on LBC. I mean I can mark payment as fraudlent from any other random trades I have done years ago, then the partner is stucked and sometimes it's not possible to provide few years old documents (depends what was traded). In my case, maybe it would be possible, thanks God.