Q: Apple iPhone 4s driver usb for windows 8.1

Hello syap_pop,

It sounds like you need the driver installed on Windows 8.1 for iOS devices. Use this section of the following article:

If iTunes doesn't recognize your iPhone, iPad, or iPod

You don't see the Apple Mobile Device USB Driver

1. Disconnect your device from your computer.
2. Save a screenshot by pressing the device's Home button and Sleep/Wake button at the same time. The screen should flash briefly.
3. Reconnect your device to your computer.
4. If you see any of these sections in Device Manager, expand them: 
    
   • Imaging Devices
    
   • Other Devices
    
   • Portable Devices
    
   • Universal Serial Bus Controllers

Now look for the entry that recognizes the device as a camera. You should see "Apple iPhone," "Apple iPad," or "Apple iPod." Right-click the device entry, then manually update the Apple Mobile Device USB Driver.

If only Unknown Device appears, follow these steps:

1. Right-click on the Unknown Device entry.
2. Choose Properties from the shortcut menu and then click the Details tab.
3. In the drop-down menu, select Hardware IDs.
4. If the ID starts with something other than USB\VID_0000&PID_0000, go to Device manager and right-click the Unknown Device entry, then manually update the Apple Mobile Device USB Driver. 
5. If the ID starts with USB\VID_0000&PID_0000, then follow the remaining steps.
6. Disconnect the device and unplug all USB devices from the computer.
7. Shut the computer down, then turn it back on.
8. Reconnect the device, testing each USB port for about 30 seconds to see if the device is recognized.
9. Test with a different, known-good 30-pin-to-USB or Lightning-Connector-to-USB cable, if available.

If you still need help, contact Apple Support.

Thank you for using Apple Support Communities.