First method:
Power on the phone.
Hard Reset SONY Xperia Sola MT27i
Then goto Settings -> Backup & reset -> Factory Data Reset -> Reset Phone.
Now select option "Erase everything", and confirm that.
Done!
Second method:
First you should download flashtool from Sony website: developer.sonymobile.com/services/flash-tool/
Make sure, that you have installed drivers for your USB data cable.
Now turn off your device.
Hard Reset SONY Xperia Sola MT27i
Then press and hold Volume Down, and connect to USB cable.
HardReset SONY Xperia Sola MT27i
Next follow the instructions in your screen, and accept appropriate options.
Success!
Third method:
Switch off your cell phone.
Hard Reset SONY Xperia Sola MT27i
Next hold and press Power button + Volume Up for about few seconds.
Factory Reset SONY Xperia Sola MT27i
Release them, when you see menu on your screen.
Now follow the instructions on your screen.
Fourth method:
First you should download PC Companion, in example from here: www.sonymobile.com/gb/tools/pc-companion/
Install it and run.
Next you will see window with 4 options.
Master Reset SONY Xperia Sola MT27i
Choose option "Support Zone New!", and click "Start".
Wipe data SONY Xperia Sola MT27i
Wait for the program to install the appropriate add-on.
After that you will see next window with 3 options.
Format SONY Xperia Sola MT27i
Goto option "Phone / Tablet Software Update", and click "Start".
Select "repair my phone / tablet".
HardReset SONY Xperia Sola MT27i
Now follow the instructions and accept all informations.
Restore SONY Xperia Sola MT27i
Remove screen password SONY Xperia Sola MT27i
Please be patient and wait until preparing computer for software update is complete.
Remove Screen Lock SONY Xperia Sola MT27i
Afterwards choose your phone / tablet model.
Permanently delete data from SONY Xperia Sola MT27i
If you see this window, then connect your device into your PC.
Hard Reset SONY Xperia Sola MT27i
Done!
Fifth method:
Power on your device.
Hard Reset SONY Xperia Sola MT27i
Now press Call button, and type: *#*#7378423#*#*
Then you will see menu.
From this menu choose option Customization Settings -> Reset customization.
Confirm information: "data will be cleared and factory data reset will perform".
Accept with pressing Reset customization and reboot.
Please be patient -> your device will reset and reboots.