While you keep on adding text that would create smiley images on the posts when displayed on front-end, but the text like ‘:)’ is not getting converted to 🙂 , then there is some issue, either with the settings or with the way you enter the text in post content in editor or the comment text area.
[recommended]You may like to read: List of Smilies Available In WordPress Default Installation[/recommended]
In case Smilies added to the content or comment text do not work on your WordPress blog installation, here is the troubleshooting checklist:
In most of the cases, the ‘Smilies’ feature is disabled thru the settings. Check if that is the issue for you.
The images for the smilies are present in /wp-includes/images/smilies directory of your WordPress root installation. The file names are like icon_smile.gif, icon_cry.gif and so on. Just check if these images for the respective emoticon exist in the folder.
If not, just upload the images to this folder.
[recommended]Read this: Replace Smiley Images In WordPress Posts and Comments[/recommended]
You should type a space before and after your smiley text. Otherwise the WordPress formatter will think that it is a normal text within the content and will not convert it to image while displaying on front-end 😉