already deleted pic of video still shows up as thumbnail

I have an iphone 3gs. I click on photos and i see camera roll (2) and photo library (6) the camera roll has a thumbnail picture or video that has been deleted or is not there when i click on camera roll. i click on camera roll and it tells me its empty which it is... so my question now is how do i delete that thumbnail on camera roll? it says there are two other images on there.. how do i delete these items? i have played and played and cant figure it out... thanks anyone for reading..