JAILBREAK IPHONE 4 IOS 7.1.2

STEP 1:
The first step for any jailbreak is to backup your iOS device so you can easily restore your device to an un-jailbroken state in case something goes wrong. You can do this either by backing it up to iCloud, which requires a WiFi connection and for the device to be connected to power, or just by backing it up to iTunes over a USB cable.
STEP 2:
After you backup your iOS device, connect it to a Windows computer via a USB cable.
STEP 3:
Launch the Pangu utility and click the grey Jailbreak button.

STEP 4:

Clicking the grey Jailbreak button will prompt a video to come up that will guide you in changing the time and date on your device to 8:30 PM on June 2nd 2014, which is needed for jailbreak exploit to work. For your convenience, the same instructions have been written here in the next step.

STEP 5:

On your iOS device, open the Settings app from the home screen and navigate to General > Date and Time and turn off the Set Automatically option. Set the time to 8:30 PM and set the date to June 2nd, 2014.

STEP 6:

After setting the date and time on the device, you should now see an icon on the home screen called Pangu. Tap on the icon, tap Continue, then Pangu will load the jailbreak onto your device. After a few moments your device will be jailbroken and the Cydia app will be loaded onto the device.