[Linking Minecraft Account]

Hi,

So I copy and pasted the link account code in game and it had an error. I've tried it a few times, but I was wondering how do it correctly? Thanks!

[Server rollback?]

Sup, 

So my friends and I were doing some other stuff and a random joined our server with hacks and literally destroyed everything. Is there any way to go back into the files and revert it back?