How to fix your chat not showing up in minecraft?

In minecraft it can't show in single player & multi player

If it's only the chat you can't see, then I think all you need to do is turn on chat in the options. Esc. Key --> Options --> Multiplayer Settings --> The first box says "Chat:"; cycle through that until it says "Shown".

If it's NOT only the chat (ou can't see your chat, on-hand inventory, health, etc.) then try hitting F1. This toggles the GUI.

Hope this helped!