With iOS 7, Apple introduced a new feature that asks you – on the iPhone/iPad – to authenticate/trust a computer that you connected your iDevice. The Trust/Don't Trust dialog has been a source of constant trouble for a lot of people while it has also worked just good for others.
Briefly, you need to “Trust” a computer to enable sync and data transfer between the iPhone/iPad and the computer. If you tap on “Don't Trust,” iTunes won't be able to recognize your device at all and so. Naturally, you can't transfer data or sync the iDevice.
Accidentally Clicked “Don't Trust” on iPhone/iPad
The Trust-dialog loop is one problem that we've addressed before. But there's another problem: what if I accidentally tapped on “Don't Trust” and now my iPhone can't sync with iTunes? You really didn't mean to do that, but accidentally, you tapped the wrong option.
How to undo this?
Usually, if you just disconnect the iPhone, wait for a few minutes and then reconnect it, you get the authentication dialog back again. But if that doesn't work, we have to find other ways.
There are two ways to fix.
#1. Resetting Dialog Warnings in iTunes
After you tapped on “Don't Trust,” there's actually no going back as long as your iPhone is connected and iTunes running. But there's a reset-warnings option within iTunes which can work. Let's first try that:
- Disconnect your iPhone from the computer.
- In iTunes on PC/Mac, click Edit → Preferences.
- Click on the Advanced tab.
- Click on the Reset Warnings button.
- Close iTunes.
#2. Disconnect, Quit iTunes, Wait and Retry
The first method is usually a sure-shot way of fixing an accidental “Don't Trust” click. 99.99% of the time, it works. In the rare event that it doesn't work, this is what you need to try:
- Disconnect iPhone from the computer
- Quit iTunes on the computer
- On the iPhone, go to Settings → General → Reset and reset all settings. (this doesn't remove the data or apps. It just resets things like Wi-fi passwords and clears cache)
- Open iTunes on PC/Mac.
- Connect the iPhone.
(Alternatively, you can switch off the iPhone and then plug it into the computer. This will power it on, and the dialog shows up after the iPhone powers on)
#3. Reset Location & Privacy
Tap Settings → General → Reset → Reset Location & Privacy → Enter Passcode → Tap on . This will reset your location and privacy settings.
#4. Reset Network Settings
Tap on Settings → General → Reset → Reset Network Settings.