Remove requirement of App Store password
I'm not too sure as to what caused the problem but all you need to do is go to:

Settings&gt;General&gt;Reset&gt;Reset All Settings


This will result in losing all the wifi passwords you connected to but you can just retype them. Then just update or download something (that's free of course like an already purchased app or an update), type in the password, cancel (unless you actually want to download it) and now you don't need your password anymore.