1. WiFi network
Rooting the phone will erase all of your data.
All described operations you are doing at your own risk.
If want saves your data do a backup before start.
The battery should be at least 50% charged before starting.
1.Turn on SONY Xperia Tipo ST21i phone and connect to WiFi network.
2. Go to Settings --> Security --> turn on unknown sources
3. Open Chrome browser and type address download.hardreset.info
4. Open directory sony them root and download aplication HardReset.info_kingroot.apk
5. Next install HardReset.info_kingroot.apk.
6. Next turn it on and swipe up untile you will see try it button.
7. Next press try it button and then try root button to root phone.
8. Just wait to process end.
That all. Your SONY Xperia Tipo ST21i is rooted. Congratulations.