<?xml version="1.0" encoding="UTF-8"?>

-<opensource_socialnework xmlns="http:/opensource-socialnetwork.org/v/1.0">

<version>5.6</version>

<stable_version>5.6</stable_version>

<release>1605286634</release>

<build>1605294860</build>

<licence>Open Source Social Network License (OSSN LICENSE)</licence>

<author_url>http://www.opensource-socialnetwork.org</author_url>

<copyright>(C) 2014-2015 Informatikon Technologies, 2015-2020 SOFTLAB24 LTD, 2014-2020 Open Source Social Network. All rights reserved</copyright>

</opensource_socialnework>

https://i.imgur.com/wW32nI9.png

Ok thanks.
Assuming your site is still https://rocknmetalbulgaria.eu/rockbook

then https://rocknmetalbulgaria.eu/rockbook/opensource-socialnetwork.xml
in fact still shows version 5.2

So, on your local PC please open the file opensource-socialnetwork.xml which is part of the archive you have formerly unzipped and make a screenshot

Thro the Jet backup from my cPanel
https://i.imgur.com/qF4Jgpq.png

How did you backup your Ossn installion and data directory?

I did a upgrade,but still on 5.2

Ivailo,
a lot of FAQs like have been answered in Documentation section https://www.opensource-socialnetwork.org/wiki/all already

Read https://www.opensource-socialnetwork.org/wiki/view/708/how-to-upgrade-ossn