My friends account hacked?

He told me that a few weeks ago his PlayStation account logged him out and asked for him to sign back into psn but just never did since he wasn’t on his PlayStation for a bit. He told me though that his Fortnite account logged him out too and a kid was playing on his account Because he joined his accounts party and heard the kid talking. I decided to help get his account back so he remembered and put in his password and he was logged into PlayStation we got onto Fortnite and it said he was logged out. We tried to reset the password but whenever we put the email it said that no account was on the email so the email must of changed. Is there anyway to get his account back I’m sure if needed he could provide more than enough evidence he owned the account (screenshots purchases skins he owns etc) any help would be welcome.