Sometimes you may need to reset your phone may be because you forgot your passcode or may be device is stuck in the boot loop. So, without wasting time, let's move on to real thing.
1. Firstly, turn OFF your device
2. Now, turn ON by holding down the power and bottom volume key, after about 10 seconds, let go of the volume down button and keep holding the volume down key. Now exclamation sign will appear on the screen.
3. Now press the following buttons in the specified order
volume up, volume down, power button, volume down
4. After this, youe device will restart and phone will be resetted.