Hard Reset SONY Xperia Acro HD IS12 SO-03D

First method:

1. Power on the phone.
   
2. Then goto Settings -> Backup & reset -> Factory Data Reset -> Reset Phone.
3. Now select option "Erase everything", and confirm that.
4. Done!

Second method:

1. First you should download flashtool from Sony website:http://developer.sonymobile.com/services/flash-tool/
2. Make sure, that you have installed drivers for your USB data cable.
3. Now turn off your device.
   
4. Then press and hold Volume Down, and connect to USB cable.
   
5. Next follow the instructions in your screen, and accept appropriate options.
6. Success!

Third method:

1. Switch off your cell phone.
   
2. Next hold and press Power button + Volume Up for about few seconds.
   
3. Release them, when you see menu on your screen.
4. Now follow the instructions on your screen.

Fourth method:

1. You should first download and install program PC Companion.
   * In example from here: http://www.sonymobile.com/gb/tools/pc-companion/
2. If all went well, you will see window with 4 options.
   
3. Next click "Start" under the name "Support Zone New!".
   
4. Wait until the process of the installation is completed.
5. Now you should see window with in example option "Phone / Tablet Software Update".
   
6. Accept this option -> click "start".
7. Then click "repair my phone / tablet".
   
8. Please follow all instructions, and confirm that.
   
9. Read "Inportant information", and confirm.
   
10. Afterwards PC Companion is "preparing computer for software update".
    
11. Next select your phone / tablet model.
    
12. Follow steps, which you see in new window.
    
13. That's all.

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.