How to allow apps access to my photos?

I recently updated my iPhone 4S and now I can't for example upload photos to Instagram.

I've gone to settings - privacy - photos but there is nothing there! It just says "apps that have requested access to your photos will appear here".

I've tried everything, please help!

Hmm, well on my 4 I followed the steps you have tried just now to double check. When I go to Settings > Privacy > Photos and I have a list of many apps that are all turned on, and instagram is one of them