At First Backup your all importune data. Before doing hard reset first check your mobile Battery status. make sure your device battery is not empty.
1. Make sure your phone is turn off
2. Now Press and Hold Volume Down Button + Power Button Until Show android robot logo.
3. use volume down key to select wipe data factory reset press power key to confirm.
4. after that select Yes
5. Finish That Select Reboot System Now wait Sevres mints.
2nd Method :
Make Sure Your Phone is turn on
Your Battery Charge should be 70% up
Now go to
Menu
>Settings
> Factory Data Reset
> Erase phone
wait few second your system will be auto restart.
done