Before you buy a new cell phone or new tablet, please try the following procedure to repair your device. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.!
Lenovo S750 hard reset
Power off your Lenovo S750 phone. Press the power to turn ON the phone. After you feel the phone vibrate Press Volume UP. When you see an exclamation mark release Volume button. Press the MENU button. In the recovery menu use Volume buttons to select Wipe data/Factory reset and use power to confirm. You can also select wipe cache partion to Reset your S750 phone. Reboot your Lenovo phone. Select reboot system now option.
and the soft way via menu option
1. From the Home screen, press the Menu Key and touch Settings. 2. Touch the Backup and reset. 3. Touch Factory data reset. 4. Touch Reset phone. 5. Touch Erase everything.