Look at the bottom of the page, where you type your replies.
Click "Go Advanced". It will take you to a new screen, where you should have all those options... insert smilies, change the font, and the size of your type.
That's odd, never heard of this happening before. If this is a new problem, try refreshing your browser. If that doesn't work, check your internet security settings and see what all it disallows you to do. Make sure you have Java enabled, as I think the WYSIWYG editor runs off some Javascripting.