How do I fix this?????

Basically, when I was back from playing a game, I opened YT and it put up a message, I was stupid and didn't read it all, the first words I read were 'your YT is corrupted and will be reset' of course I pressed cancel, but my account is gone, and I had the account since I was a kid, and at the time I asked my brother to do it as I didn't know how, and it's linked to his phone, but I don't know the stuff for it, and he doesn't know where his phone is, so I can't log back in, does anyone know how to fix this???