How can I download the software for iPhone 4S... Right now I have a useless version for my phone I think is the one for the iPhone 5S

What do you mean by go back? What version of iOS do you now have installed?

Apple has never supported downgrading an iOS version, and removes the older iOS version files from the servers when the new version is released. So there is no means of going back.

That does not make sense. The iPhone 4s and iPhone 5s along with all other iPhones after that run the exact same software version. If you are having issues with an iOS update, explain what issues you are having and we may be able to help resolve them.

Frankflow wrote:

YYeah I would like to go back to a useful version

The current iOS version, iOS 8.4, is the only version you can download, the older versions no longer exist on the Apple servers.

Have you checked to see that the apps you use are fully updated?

What happens when you try to use the apps?

Have you attempted to Reboot the iPhone?

Restore the iPhone?

Note that the Health App will not get any health data directly from the phone since it does not have the motion coprocessor required. It will depend on other Apps like Nike + Running or similar to get data into it.