If your iphone cannot be found : can be a hardware problem :
- try with another usb/lightning cable
- connect to another usb port on your pc
- check if there's no dirt/dust inside the lightning connector port on your iphone (happened to me : my phone didn't charge anymore. After removing the dirt it worked again. Carefully remove dust with a fine brush - be very very careful not to damage the internal contacts - I don't recommend using a needle)
- or maybe the lightning port on your iphone is broken (mine broke down for audio, when wiggling the lightning plug /cable it sometimes worked/didn't work for audio output, I guess this can affect data traffic too) -> then a repair shop is your last option.
some other possible fixes found on the web : (I just googled your error message)
2. Check Apple Mobile Device USB Driver
Sometimes, iTunes fails to recognize your iPhone because the Apple Mobile Device USB driver is not or improperly installed. So you can check Device Manager to see if the Apple Mobile Device USB driver is rightly installed. Follow these steps to open Device Manager:
Press the Windows and R key on your keyboard to open the Run command.
In the Run window, enter devmgmt.msc, then click OK. Device Manager should open.
Locate and expand the Universal Serial Bus controllers section.
Look for the Apple Mobile Device USB driver.
3. Uninstall the Antivirus or Firewall Apps
Sometimes, the antivirus or firewall apps may cause the connection failure between iPhone and PC, and that's why the iTunes can not recognize your iPhone. To solve the issue, you can uninstall the antivirus and firewall apps temporarily. After iTunes detects your iPhone and finishes restoring, you can reinstall those apps.
4. Update iTunes to the Latest Version
Generally the issue of restoring, including the error message 'The iPhone cannot be restored. The device cannot be found', arises when the iTunes application is not updated to its latest version. To get this done, here's the step by step tutorial.q
6. Restore with iTunes using Recovery Mode
In this section, we are going to know how to use the 'Recovery mode' to restore your iPhone to factory settings with iTunes. This only works for people who have never tried this method.
Launch iTunes on your computer and connect your iPhone with your computer using the lightning cable.
Put your device into Recovery mode. When your iPhone is in recovery mode, you will see the "Connect to iTunes" logo or a cable pointing to the PC on the screen.
iTunes will detect your iPhone in recovery mode and ask you to restore your device. Click OK on the screen and then click Restore iPhone to get your iPhone restored. Wait for a short while and it will finish soon. Then you can set up your iPhone which is like a new device now.