iPhone contact issue

[seniorpaul]

I recently noticed that I have a problem with my contacts on my iPhone. While all my contacts are still listed in alphabetical order, they're no longer subdivided by letter. So I can't tap a letter on the side to jump to those contacts. Any NEW contact I add is in the right spot though. So I have a couple of contacts seperated at the top, then all my older contacts listed alphabetically undernieth. Any idea how I can get them all divided by letter again?