I have been playing this game for months now with no problems. Today when I started the game it was windowed and there was no text at all. I attached some screenshots so you can see what I'm dealing with. Any help would be great.
Try verifying your game cache.
Right click killing floor, click Properties, then the Local Files tab and then "Verify Integrity of Game Cache." Steam will check all the files to see if any of them are messed up, and redownload anything it finds problems with.
Try deleting the system.ini file.