Im gonna cry i need help

I played this game for a while, did literally everything have every item all quests done amd got every special weapon attack and ability. And recently, My cousin just made a character and I joined his game on shared progression thinking everything is fine. Turns out, nope. Now every special weapon ability is gone. Any progression with anything is poof. And yes I tried to see if there was a backup save. There isn't even tho I clicked yes. Is there a way to get my old save back? Or could I join a guy that also 100% completed this game on shared progression so I can get all the quests done again???