In order to hard reset a LG U300, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
LG U300 device will be brought back to the default configuration of a brand new device.
1. For starters, turn on the device.
2. Press the Call button in order to open the dialer.
3. Enter this sequence into the dialer: either 2945#*101# or 1809#*101#
4. To complete the hard reset process, press the Call button. Wait for your device to reset and restart.