reboot your system and it should work again
Reboot your system and if that doesn't work and if you are familiar with the files that need to be on your Crossfire folder go double check those, if you see a file missing check your deleted folder (trash) and put it back where it needs to be, if a file is deleted which most likely is the case, delete ALL the files and re-download and re-install the game files and it should work fine.