Fidget Lego

Soooo.... I banned myself from single-player for ten years. How can I undo this? I was messing around with commands, and I accidentally hardbanned myself (thinking it would be more of a kick, from Minecraft experience). Unfortunately, it affects every single-player world I have, so unless. I fix this or buy a new account, I am permabanned from singleplayer for ten years.... Can someone tell me how to revert it?