Why won't my iPhone 4 update IOS 7?

My question is up there, no details.-.

4s and above will work with it.
Get a new iPhone if you want it.

Well, the question is very brief, so there might be a lot of reasons why it won't update.
First, check your Internet connection. The iPhone will update the best when connected to a Wi-Fi network. Don't bet on 3G/4G.
Next, try rebooting your phone. This may clear up some background processes that are clogging up your phone. Also, quit all your apps are running by double clicking the home button and pressing and holding on one of the apps and clicking all the red circles. This doesn't delete your apps, it just closes them like on a computer. If all that doesn't work, you can call Apple support. Of course, you would have to call using another phone other than your iPhone for them to help you with the update. They are the nicest customer support technicians in the world, and they'll understand your problem better if you explain it thoroughly to them.

If you have a computer, you can download iTunes for it, and plug in your iPhone into the computer using your charging cable and update it through iTunes. Updating usually works a lot better through a computer because it has a stronger Internet connection and is less prone to mess up the downloaded file.

Hope this helps.

I just got an iphone 4 and it worked fine. I had to redo it cuz i didn't have Wi-Fi and it wouldnt verify. I went to my settings, clicked software update and updated.