I went into my friends realms and ended up participating in hell

The title is a metaphor, but it's that serious of a problem. The world is bugged. Almost everything has turned into strange blocks, and at first I found it novel and laughed out loud, but as time went on I realized I was in a critical situation. I don't even know which block is what. None of my friends are experiencing this bug, so this bug is only affecting me. I can open the

Marketplace. Textures work fine in my world and on the hive server. I'm only in one Realms, so I can't verify what's happening in other players' Realms.