If you have installed a new version of iOS, or have otherwise modified your iPhone or iPad and are now running into problems that you cannot seem to overcome, then a quick fix is to restore your phone to a recent backup. These issues may especially happen if you have installed test versions of iOS from Apple, such as a public or developer beta of the latest versions of iOS. While you may wish to simply downgrade your iPhone or iPad, unfortunately Apple provides no utility for this. Therefore, your only approach is to use a backup of your device that you made before upgrading or modifying your device, so hopefully you created one before upgrading or modifying your device.
Even with a backup, simply going to iTunes and clicking the options to restore your device from the backup may not work. If you see any warnings or errors that pop up and prevent you from restoring your iOS device, then you can force the restoration by doing so in Device Firmware Update mode–a special mode that allows restoration of your device from any state.
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- Then connect it to your computer and open iTunes.
- Press the power button and then immediately hold the home button at the same time.
- Release the power button after 10 seconds.
- iTunes should show a notice that says the device is in Recovery Mode.
- Go to the Summary tab for the device in iTunes.
- Hold the Option key (or the Shift key if you are on a Windows PC) and click the “Restore…” button.
- Select your desired backup (using the time stamp in its file name).

When in Device Firmware Update mode, iTunes will show the device as being in “Recovery Mode.” From here Option-click (or Shift-click in Windows) the Restore iPhone button to select a backup to apply to your device.
At this point, confirm you wish to restore your phone, and then wait for iTunes to fully copy your backup to your phone. This may take a while, but when done, your phone will restart normally and should have the backup running. Be sure to fully test your phone at this point, to ensure all features, software, and services work as expected.
I always was under the impression that once you upgraded from, say, iOS 6 to iOS 7, you could not go back because Apple is pulling the relevant signatures for those versions. Can I still go back from 7 to 6 with your method today?
If you have a old device like before iPhone 4, you might be able to, but if you have anything newer, you sadly cant.