How to put iphone pics on my computer when my computer says it doesn't have any?

I want to import my pics from my iphone4 to my computer but the computer says it doesn't have any when i know it does i've done it before but i just doesn't do it anymore

There are some great iPhone/iOS apps that will let you basically turn your phone into a web server for your photo library on your device. You run the app, turn on the server in the app, and then on your computer you can type in the address that the app tells you to type, like you're visiting a web page on the Internet only its your phone! Once you are connected, you can browse your Photos folder on the phone and download the ones you want. When you are finished, you simple turn off the application on your phone and go about your next task for the day. Very slick!

The specific apps I have on my phone are Wi-Fi Photo, Media Folders, and PhotoShare (which uses bluetooth instead of wireless)

I sometimes find this more efficient than trying to import through iPhoto and such, although that is pretty simply and a lot faster too if you are connected with the USB cable directly into your computer.