Recently I've had a problem with not being able to use my keyboard during single player. It just simply doesn't write whatever I'm typing, and it's getting really annoying, because I can't even save games. I'm on google chrome playing the unity version.

https://www.warzone.com/ReportBug

Thought keyboard not typing only happens to me. For me this only happens when I use Flash on FF. Try typing in the search/address bar then you'll probably be able to use your keyboard on Warzone again. That sorts it for me anyway.

When I had this issue in Google Chrome, it's because the keyboard focus wasn't inside the Unity game. Even clicking inside the game area didn't do it, so instead the solution was to repeatedly press tab and try to type something until it appeared in the chat box. Eventually pressing the tab key will move the focus into the game and it will pick up all the keyboard presses.