You need to be logged out of to start recovery process.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3456188107

What counts as viable proof of ownership:
https://psteamhelp.yuanyoumao.com/en/faqs/view/40A0-8B4B-B54B-C51A

Thanks

good luck with your account

Everyone needs to stop using the term hacked. Accounts are not hacked, but hijacked. Your friend either clicked a link, voted for something, logged into a third-party site using Steam, etc. Hijackers could been in the account for years before they do anything. They wait until the account has something of value to steal.

My apology sir for using the term "hacked"