If you can’t turn HTC Desire 300 on or access settings, you can still perform a factory reset by using the hardware buttons on HTC Desire 300.

1. Remove the battery, wait for a few seconds, then reinsert the battery.
2. Press and hold the VOLUME DOWN button, and then press and hold the POWER button.
3. Wait for the screen with the three Android images to appear, and then release the POWER and VOLUME DOWN buttons.
4. Press VOLUME DOWN to select FACTORY RESET, and then press the POWER button.