Recovery, in Android, refers to the bootable partition, in which the recovery console is installed.
It contains tools to help repair your installations as well as install official OS updates by using a combination of key presses or instructions from a command line sometimes.
Android is open, meaning the recovery source code is available, so that building a customized ROM is relatively easy.
1. First thing to do is turning off your device by holding down the power button.
2. Now wait a moment and start from holding down power button with volume down key together.
3. Now when your phone's screen will show LG logo you can let go off the buttons.
4. And now your phone should be in Recovery Mode, done!