Step 2. In the Control Panel uninstall Apple Mobile Device Support, Apple Application Support, iCloud and iTunes 12.1.
Step 3. Change the extension on your iTunes Library.itl file to iTunes Library.bak. you can fin this file in C:\Users\YourUSERNAME\Music\iTunes.
Step 4. When you’re done reboot your Windows machine
Step 5. When you computer reboots you’ll now be able to install iTunes 12.0.1.
Step 1. Download Pacifist from Pacifist.com and install it
Step 2. Quit iTunes, remove all its traces using Activity Monitor
Step 3. Download iTunes 12.0.1 for OS X and mount it but don’t install it
Step 4. Launch Pacifist, which you downloaded is earlier
Step 5. Click on Open package > iTunes under Device in the left side bar.
Select Install iTunes and then Open in the bottom right corner
Step 6. Click on Contents of Install iTunes then select Install from the top bar. Follow the on screen instructions until installation begins
Step 7. After a few minutes, you should see a box saying Application already exists. Check Don’t ask again for this installation box and click on Replace
Step 8. Wait for some time until the process is completed
Note: If it still doesn’t work, use the Microsoft Troubleshooter at. Let it run and select the problem with your software. A list of programs will show, select iTunes. The Troubleshooter should move the muscle for you.
Downgrade iOS 8.1.3 To iOS 8.1.2
Step 1: Download iOS 8.1.2 from here for your iPhone, iPad or iPod touch. Make sure you download the correct firmware file otherwise iTunes will instantly reject the firmware and you’ll be prompted with an error message.
Step 2: If you haven’t yet, create a backup your iOS device either using iCloud or by using iTunes.
Step 3: Plug your iOS device to your PC or Mac, launch iTunes, hold down the left SHIFT key on PC (or the OPTION key on Mac) and click on the “Restore iPhone” button. Select the iOS 8.1.2 firmware file you downloaded in Step 1. now you can take a ten minute break, grab something to drink, and let iTunes do the rest.
In about ten to fifteen minutes you’ll be back to iOS 8.1.2, ready to jailbreak your device using TaiG.
Note: Once Apple stops signing the iOS 8.1.2 firmware, you won’t be able to downgrade back from iOS 8.1.3. So hurry up. Apple might be closing the signing window anytime.
Let me know if this worked for you in the comments section down below!