It was working a couple of days ago when you put the banner ad in the header. What have you done since?
Have you retraced your steps back to when the site was last working? I would start undoing all the recent mods/changes, in order, from the most recent (keeping records/copies of code etc. along the way). Otherwise, you may have to adopt in shotgun approach and start doing things like temporarily disabling all plugins or changing the theme to see if things reappear.
hey yes it was working fine, but i really have no clue what has happened its very strange i realise i have done something but can not think what it is off the top of my head i cant remember doing anything drastic that may have caused this?